You can't forget to put on the sunscreen/sunblock!
You can't forget to put on the sunscreen/sunblock!
日焼け止めを塗り忘れちゃだめ！
You need to 〜：〜する必要がある！という言い方でもニュアンスは同じです。
put on：〜を塗る
sunscreen/sunblock：日焼け止め
厳密にはsunscreenとsunblockには違いがあるようですが、成分の違いでどちらも日焼け(sun tan/sunburn )からお肌を守ってくれるものとしては共通です！
"You can/can't do without." We use this construction when talking about things we need and do not need.
"I can't do without my laptop. I use it for work and for pleasure."
Indispensable = Something that you need and cannot do without.
"Having a friend with her at this difficult time is very good for Sarah."
"A bare necessity," is one of the most basic things you need.
"All I need is the bare necessities of life to be happy!"
"You can/can't do without." この文法は、必要なこと、必要ではないことを話すときに使います。
"I can't do without my laptop. I use it for work and for pleasure."
仕事をするにも趣味にしても、パソコンは欠かせない。
Indispensable = 必要不可欠の
例
"Having a friend with her at this difficult time is very good for Sarah."
この難しい時期に友達ができるのはサラにとってとても良いことね。
"A bare necessity," これは一番根本的に必要なものという意味
"All I need is the bare necessities of life to be happy!"
幸せに生きるために根本的に必要なもの、それだけで充分さ。
You can not go without sunscreen/suncream in the summer
Sunscreen/suncream is indispensable in the summer
When the weather is hot 'sunscreen', 'suncream' or 'suntan lotion' is a must and should be worn to protect your skin against getting burnt
So you could say Weating sunscreen is 'a must' meaning you have to do something (must do it)
Indispensable means youhave to do something and it is a necessity (you need to do it)
暑い日には、肌を守るための日焼け防止である”Sunscreen"、”Suncream"、”Suntan Lotion"は必需品です。
●”Wearing a sunscreen is a must"
（日焼け止めを塗るのはマストだ。）
Mustは「必ずしなくてはならない」、Indispensableは「欠かせないもの、なくてはならないもの」という意味です。
Native speakers will say like this: “Sunscreen is essential during the summer”.
There are lots of other ways to say it, but this one is the most accurate and most commonly used.
Here is an example on how to use this in a conversation:
A: If you're going to the beach put on sunscreen! It's essential in this time of the year.
B: Okay, mom.
ネイティブスピーカーなら、このように言います：
“Sunscreen is essential during the summer”.
（夏の間は日焼け止めが欠かせません）
他にもいろいろな言い方ができますが、これが最も正確で一般的です。
会話で使うと次のようになります：
A: If you're going to the beach put on sunscreen! It's essential in this time of the year.
［訳］ビーチに行くなら日焼け止めを塗りなさい！この時期は絶対必要よ
B: Okay, mom.
［訳］分かったよ、お母さん
It's important to protect yourself from the harsh summer sun rays by wearing sunscreen.
Always make sure you wear the right sunscreen during summer.
Sunscreen is crucial during summer
"It's important to protect yourself from the harsh summer sun rays by wearing sunscreen."
You are stating a fact and explaining the reason why it is important.
""Always make sure you wear the right sunscreen during summer."
This is a reminder to wear sunscreen that is best suited to the temperature.
"Sunscreen is crucial during summer"
crucial = very important
"It's important to protect yourself from the harsh summer sun rays by wearing sunscreen."
①夏の強い日差しから自分の身を守るために日焼け止めを塗ることは重要です。
あなたは事実を述べていて、何故そのことが重要なのかを説明しています。
""Always make sure you wear the right sunscreen during summer."
②夏の間は、常に適した日焼け止めを塗ることを心掛けましょう。
気温に適した日焼け止めを塗ることを忘れないように注意を促している。
"Sunscreen is crucial during summer"
③夏の日焼け止めは、きわめて重要です。
Crucial＝きわめて重要
The three sentences you see provided above are great ways to express to your listener that using sunscreen during the summer is a must for you. In the first sentence you will see the adjective necessity and in the third sentence you will see the adjective essential. Both of these words mean very important. These words are appropriate for both formal and informal settings.
日本 
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南アフリカ 
アメリカ合衆国 
