10.However frequently he in doing the experiment, he never loses his confidence.
A
defeat
B
gets defeated
C
was defeated
D
will defeat[来源:学*科*网Z*X*X*K]
句意为：无论什么时候实验失败，他都没有放弃过。描述的是通常情况，使用一般现在时表达。所以选择B。
此题是时态辨析，首先要明确句意，其次判断缺位单词。
时态。