Question

David didn’t give up ______ he had failed in the experiment four times.

A．if

B．while

C．though

D．since

Answer 1

C

考查状语从句。句意“大卫没有放弃，尽管他做实验已经失败四次了。”A引导条件状语从句；B引导时间状语从句；C引导让步状语从句；D引导原因状语从句。故选C。