What should have been found with the letter？A．A copy of the contract.B．Related materials o

If fuel tank levels are found to have increased after a grounding, you should suspect ____

______ many times, this radio receiver is found very sensitive.A．Being testedB．Having been

【C17】A．must have beenB．may have beenC．could have beenD．should have been

He should have been a young officer.

Many ways have been found______small and simple machine to process large and complicated m

I should like to___ touch with old friends but I have been so busy with my study.