______ is too difficult if you put your heart into it.

On April 12, 1961，_____27—year—old Yuri Gagarin(尤里.加加林)became the first human to go into_____ space.

Why is Simon ________ crazy _________ playing computer games?

How soon ______ all the work ______?—In a week.

The books on my table are cheaper than_______ on yours.