By the time i——back they——up ten metres.A came.have climbed B came.had climbedC come.have climbed D had come.climbed

By the time i——back they——up ten metres.A came.have climbed B came.had climbedC come.have climbed D had come.climbed
By the time i——back they——up ten metres.
A came.have climbed B came.had climbed
C come.have climbed D had come.climbed

By the time i——back they——up ten metres.A came.have climbed B came.had climbedC come.have climbed D had come.climbed
B
by+过去时间,主句用过去完成时态.

B came。。。had climbed
By the time 要用过去时，所以我回去用came，而他们已经爬高了用had climbed，回去都已经过去了，而他们‘已经爬高了’这个动作发生在‘回去’这个动作之前，‘过去的过去’，要用过去完成时

我得到这份工作纯属巧合——我只是在适当的时候出现在适当的地方了 我得到这份工作完全是运气，我在正确的时间出现在了正确的地方/天时地利。 我