Question

5. He always helps me,but never asks for any reward,                  his sincerity. (convince)

他总帮助我，但从不要报酬，这让我坚信了他的诚意。

Answer 1

5. which convinces me of考查非限定性定语从句和convince的用法。convince sb. of sth.让某人坚信某事。