A serious study of physics is impossible some knowledge of mathematics.
A．against B．before C．beyond D．without
It was only after he had read the papers Mr. Gross realized the task before him was extremely difficult to complete.
A．when B．that C．which D．What
It may not be a great suggestion. But before _______ is put forward, we’ll make do with it.
A．a good one B．a better one C．the best one D．a best one
The watch was very good, and he 20 percent down for it.
A．paid B．cost C．bought D．Spent
We very early so we packed the night before.
A．leave B．had left C．were leaving D．have left
Since nobody gave him any help, he have done the research on his own.
A．can B．must C．would D．Need
