他の先生らが最も定番の "hang in there!!” と紹介してくれていますので、ここではあえてまた別の言い方も紹介しますね。
一つは、"Don't stop!!”，これは直訳すると "止まるなっ！！” という意味になりますが、この場合の状況の中で使えば対象を "頑張ること” 、"努力すること” などを意味した表現として "がんばれ～！！” というニュアンスをもった表現として使うことができます。
【応用編】
”Don't stop now, you're almost there!!" （あともう少し、ここであきらめないで～！！）
"Don't stop until you guys are all the way through!!" （最後までがんばっていこうぜぃ！！）
また、"Keep going, guys!" は、”頑張り続けて～！！” という意味合いに。これも同じく "さぁ～がんばっていこうね～！” という意味で使えるもう一つの言い方になりますね。
"Keep it up!!" という最後の例もまた、"（その勢いを）維持して～！！” → ”がんばれ～！！” という意味として使うことができます。
また英語の場合は日本語と違っていつでも気軽にサッと英語の "ことわざ” や昔ながらの "言い伝え” を使って伝えることが多々。この場合においても、最後の例文の表現を使った定番の一句、"Keep up the good work, guys!!" （その調子を維持して～！！）、（その調子で最後まで行こうぜぃ！！）、（最後までがんばって～！！）というような意味で使えますね。
他の先生の回答に合わせて参考にしてみてください。
Keep going
Means to make an effort to continue with something
Don't give up
Means to continue and believe in yourself and your abilities
Hang in there
Means to remain persistent and determined in difficult circumstances
__________________________________________________________
Example
A: I don't think that I'll be able to finish this marathon
B: Hang in there, my friend
Keep going
Means to make an effort to continue with something
Keep going! そのまま続けて！やり続けて！
Don't give up
Means to continue and believe in yourself and your abilities
Don't give up 自分を信じて諦めないで。
Hang in there
Means to remain persistent and determined in difficult circumstances
Hang in there 踏ん張れ！諦めないでがんばれ！
__________________________________________________________
Example
A: I don't think that I'll be able to finish this marathon
B: Hang in there, my friend
≪例文≫
A. マラソン完走できないと思う。
B. あきらめないでがんばって！
B) It's not over until the fat lady sings! hang in there!
C) You've got this! Hang in there!
A) Come on you can do it!
Example - "Come on Kyle! you can do it!!! "
B) It's not over until the fat lady sings! hang in there! -
*It's not over until the fat lady sings! - This is an expression which means :used for saying that it is still possible for a situation to change.
C) You've got this! Hang in there! -
*You've got this - used to tell someone that you believe they can or will succeed in de
*Hang in there -Don't give up/remain persistent and determined
I hope this helps :-)
A) Come on you can do it!
Example - "Come on Kyle! you can do it!!! "
がんばれ！あなたなら出来る！
例文：カイル、がんばれ！あなたになら出来るよ！
B) It's not over until the fat lady sings! hang in there! -
*It's not over until the fat lady sings! - This is an expression which means :used for saying that it is still possible for a situation to change.
まだ終わってないよ！まだまだこれからだよ！It's not over until the fat lady sings＝最後まで何が起こるかわからないから、最後まであきらめないこと。
C) You've got this! Hang in there! -
*You've got this - used to tell someone that you believe they can or will succeed in de
*Hang in there -Don't give up/remain persistent and determined
できるよ！あきらめないで、がんばれ！You've got this＝あなたになら出来る！Hang in there＝あきらめないで、がんばれ！
If you tell someone who is on the verge (an extreme limit beyond which something specified will happen} of giving up, 'winners never quit', you are telling that person to 'keep his/her determination and focus, and never stop trying'. This is a mental attitude that successful people have in sports and all walks of life.
So, you may say: Don't give up. Winners never quit and quitters never win.
If you tell someone to 'hang in there', you are encouraging them to keep trying to do something and not to give up even though it might be difficult.
You may say: Hang in there. There is still a lot of time for you to turn the game around.
もしあなたが誰か崖っぷちに立たされている人（特定の何かを超えた極限の限界）に 'winners never quit'と伝えたら、それは'keep his/her determination and focus, and never stop trying'（彼らの決意を保ち、集中しなさい。そして挑戦を諦めるな）ということを伝えています。
これは成功した人々がスポーツや職業でもつ精神的な態度です。
例：
Don't give up.
Winners never quit and quitters never win.
ー決して諦めるな。
勝者は決してやめないし、やめる人は決して勝たない。
もしあなたが誰かに'hang in there'と伝えた場合、彼らに何かを挑戦し続けることを促し、それが難しいとしてもやめないようにと伝えています。
例：
Hang in there.
There is still a lot of time for you to turn the game around.
ー頑張って。
まだゲームをひっくり返す時間がたくさんあるよ。
*You can do this.
This is a way to encourage them. It means that you believe in them that they will win.
*Don't give up. You almost there.
This mean that you haven't lost yet. If you work a bit harder you are going to win.
例文
*You can do this.
あなたならこのことができるよ。
これは人を励ます言い方です。その人のことを信じていて、勝てるだろうということです。
例文
*Don't give up. You almost there.
諦めないで。もう少しだから。
まだ負けたわけではないので、もう少し頑張れば、勝てるということです。
1. We want to encourage our team mates to win even though we are currently losing so we can say "you can do it" or it's not over yet" to emphasize the possibility of winning still being attainable.
2. There are many alternatives so you can simply use common expressions to motivate and encourage others.
1. 負けているときに自分のチームメイトを励ましたいときに使います。
You can do it!/it's not over yet! で、勝つ可能性を強調して集中するよう促すわけですね。
2.励ましには 色んな言い方、言い回しがあります。
There are many possible things supporters can shout from the sidelines to encourage their team. However in the situation where your favourite team is losing and perhaps time is running out, the only way the game can be turned around is by attacking and improving the present scoreline.
These expressions are designed to fire up the attack and aggression levels.
To encourage a teammate during a match, especially in the case where you are on the verge of losing, you can say:
"You can do it!"
"Hang in there!"
"You've got this!"
試合中、特に負けそうなときに、チームメートを鼓舞したいなら、次のように言えます。
"You can do it!"（あなたならできる）
"Hang in there!"（頑張れ）
"You've got this!"（あなたならできる）
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