Some athletes do not have contracts with sponsors.
"Not all athletes are contracted by sponsors." This is a way of explains that some athletes do not have a signed contract/agreement with a sponsor.
"Some athletes do not have contracts with sponsors." This is another way of explaining to people that only some athletes have a signed contract with a sponsor and others do not.
"Not all athletes are contracted by sponsors."
（全てのアスリートがスポンサー契約をしているわけではない）
これは何人かのアスリートはスポンサー契約していないと説明する表現の一つです。
"Some athletes do not have contracts with sponsors."
（何人かのアスリートはスポンサー契約をしていない）
これはもう一つの表現で何人かのアスリートはスポンサー契約をしているけど、していないアスリートもいる、という説明になります。
Unsponsored - means not supported by or employed by a sponosr.
‘There are heaps of prizes for sponsored and unsponsored skateboarders, so sign up now for a chance to win.’
‘Last weekend, at Atlanta, Carter fielded Nemechek's unsponsored car; Bodine stayed home.’
‘Although unsponsored and therefore without funds for extensive advertising, the exhibition nevertheless attracted much interest and acclaim.’
‘If Roush Racing can't find another sponsor for Jeff Burton's car, will the team be shut down, or will it go unsponsored?’
‘I know exactly what some of these guys feel like who have an unsponsored car - we did not have a sponsor.’
Unsponsored -これは支援を受けていない、スポンサーによって雇われていない、と言う意味になります。
【例】
‘There are heaps of prizes for sponsored and unsponsored skateboarders, so sign up now for a chance to win.’
（山のようにたくさんの賞がスポンサー契約しているスケートボーダーにもスポンサー契約していない選手にもあります。さあ、優勝するチャンスの為に、今すぐに申し込みしましょう）
‘Last weekend, at Atlanta, Carter fielded Nemechek's unsponsored car; Bodine stayed home.’
（先週末アトランタで、カーターはNemechekのスポンサー契約していない車を公認しました。ボーディンはホームにいました）
‘Although unsponsored and therefore without funds for extensive advertising, the exhibition nevertheless attracted much interest and acclaim.’
（スポンサー契約をしていなく広告収益などの資金もないにもかかわらず、その展覧会は多くの興味と称賛を集めた）
‘If Roush Racing can't find another sponsor for Jeff Burton's car, will the team be shut down, or will it go unsponsored?’
（ラッシュレーシングはジェフバートンの車に他のスポンサーを見つけられなければ、チームは閉鎖するかスポンサー無しで行くの？）
‘I know exactly what some of these guys feel like who have an unsponsored car - we did not have a sponsor.’
（スポンサー無しの車のレーサーたちがどんな気持ちかよく分かります。
僕たちもスポンサーがいませんでした）
Sponsorship is when a business provides funds or resources to someone. In return, the business gets some kind of benefit (e.g. free advertising for their business on the athlete's uniform).
If an athlete does not have a sponsor, they may have to support themselves financially by working, in addition to their sporting commitments.
You can phrase this as 'sponsor contracts' but more often English speakers will refer to this as 'sponsorships' (same meaning: when a company gives money to someone to support them).
Endorsement - when a famous person appears in an advert to say that they approve of or use a certain product
To explain that an athlete competes without money given to him or her from a company, we can say the following:
1) Some athletes don't have contracts from sponsors.
and
2)Some athletes don't have sponsor contracts.
The word 'contracts' can be modified to communicate that it is a special contract from a sponsor by using either 'contract + from a sponsor' or 'sponsor + contract'.
会社からお金をもらわずに活動するアスリートについては、次のように説明できます。
1) Some athletes don't have contracts from sponsors.（アスリートの中にはスポンサーと契約していない人もいる）
2) Some athletes don't have sponsor contracts.（アスリートの中にはスポンサーと契約していない人もいる）
それがスポンサーとの特別な契約であることは、'contract + from a sponsor' かあるいは 'sponsor + contract' で表せます。
Some of the athletes are yet to obtain sponsorship.
There are some athletes who are still unsponsored.
You can use a negative with the word 'sponsorship', such as "Some athlete's haven't got sponsorships." or "Some of the athletes did not obtain a sponsorship deal."
Alternatively, you could use the word 'unsponsored' as an adjective to refer to the athletes, such as "Some of the athletes are unsponsored." or "There are still some unsponsored athletes.". Unsponsored means to not be promoted or supported by any form of sponsorship.
否定語と共に 'sponsorship' という言葉を使うことができます。
例えば：
"Some athlete's haven't got sponsorships."（アスリートの中にはスポンサーと契約していない人もいます）
"Some of the athletes did not obtain a sponsorship deal."（スポンサーと契約しなかったアスリートもいました）
または、形容詞の 'unsponsored' を使ってアスリートを説明することもできます。
例えば：
"Some of the athletes are unsponsored."（スポンサーと契約していないアスリートもいます）
"There are still some unsponsored athletes."（まだスポンサーと契約していないアスリートもいます）
'unsponsored' は「スポンサーの支援［後援］を受けていない」という意味です。
In order to explain that some athletes do not have sponsor contracts, you can do so in the following ways:
"Some athletes are unsponsored."
"Not all athletes are sponsored."
"Not all athletes are sponsored."
「アスリートの中にはスポンサーと契約していない人もいる」は、次のように言えます。
"Some athletes are unsponsored."（スポンサーと契約していないアスリートもいる）
"Not all athletes are sponsored."（アスリートの中にはスポンサーと契約していない人もいる）
"Some athletes don't have a sponsor."（スポンサーと契約していないアスリートもいる）
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