The shocking news made me realize terrible problems we would face.
| A．what | B．how | C．that | D．why |
They became friends again that day. Until then, they _______ to each other for nearly two years.
| A．didn't speak | B．hadn't spoken | C．haven' t spoken | D．haven' t been speaking |
As the years passed, many occasions—birthdays, awards, graduations—________ with Dad’s flowers.
| A．are marked | B．were marked | C．have marked | D．had marked |
As the twentieth century, come to a close, the raw. materials for a great national literature were at hand, waiting_______.
| A．to use | B．to be used | C．to have used | D．to be using |
With the help of high technology, more and more new substances____in the past years.
| A．discovered | B．have discovered | C．had been discovered | D．have been discovered |
—You speak very good French! 
—Thanks. I __________ French in Sichuan University for four years.
| A．studied | B．study | C．was studying | D．had studied |