sink or swim

沈むか浮かぶか, のるかそるか, 一か八(ばち)か.

(一所懸命頑張ってなんとか成功させるか失敗する

1.

The best way to test someone's character is to put them in a tough situation and let them
sink or swim.

2.

His parents have stopped giving him money and said now he would have to sink or swim
on his own.

3. She was thrown in the deep end and it was either sink or swim.