Some insects_______ the colour of their surrounding to protect themselves.

If you cheat in the exam, you could hardly _________ it.

 I’m sorry to say you didn’t pass the exam-- ______, you won’t receive the diploma.

Low-carbon lifestyle is of great benefit to improve the world environment, but the problem is difficult to _________．

Yet ever since then, people at home and abroad have ________ different opinions about the policy.