单选题 Racing the clock every day is such an exhausting effort that when I actually have a few free moments, I tend to collapse .
【正确答案】 A
【答案解析】[解析] 句意为:每天争分夺秒的工作让人精疲力竭,以至于当我确实有些自由的时间时,也常常会倒下。collapse“塌陷”,四个选项:fall down“掉下;倒下”;fall in“病倒”;fall out“吵闹,争吵”;fall behind“落后”。所以A项符合题意。