He challenged me to a sit-up contest.

他挑战我进行仰卧起坐比赛。

Doing a sit-up incorrectly can strain your back.

不正确地做仰卧起坐会拉伤你的背部。

I do a sit-up every morning to strengthen my abs.

我每天早上做一个仰卧起坐来锻炼腹肌。

A proper sit-up requires you to keep your feet flat on the ground.

正确的仰卧起坐要求你双脚平放在地上。

Which is supported by a structure too expansive for a sit-up.

这由仰卧起坐结构支撑起来太大。

Objective To assess the diagnostic value of the atropine test and sit-up exercise for sinus node function.

目的评定阿托品药物试验联合仰卧起坐运动对窦房结功能的诊断价值。

Which is supported by a structure too expansive for a sit-up .

而之一切都是由结构上大的起伏所支撑起来的。