_______ have you been learning English? —So far, more than 10 years. [ ]

I have to study for my English test _____Friday.[ ]

Be sure _______ when you enter the cave. Otherwise, you’ll hit your head on the rocks.

I am leaving for a vacation.-Really? Where ________you __________?

What do you think of this math problem?—It’s too easy. _____ in our class can work it out.