He _____ articles for our wall-newspaper these three years, and he _____ about forty articles

He _____ have completed his work; otherwise, he wouldn’t be enjoying himself by the seaside．

Can you explain ______ the OPEC can have such total control over the price of oil?

The robbers searched all the boxes in the house, hoping to __________more valuables

Who do you think _____ such a foolish thing?– It _____ Tom, but I’m not sure.