If you don’t study hard, you’ll regret, _____ you?

Could you show me how to ________ this new recorder?

I am twelve and I like English. — Oh, really? I am twelve and Ilike English.

How many students are there on the playground? —_________.

The earthquake in Japan, measuring 9.0 on the Richter Scale, was so violent cause a series of explosions of the nuclear reactors in several power stations.