According to the data, China supplies more than 90 percent of the world’s rare earth metals, but its reserves only about one third of the world’s total.
| A．take up | B．build up |
| C．make up | D．polish up |
Now that she is out of job, Lucy __________ going back to school, but she hasn't decided yet.
| A．had considered |
| B．has been considering |
| C．considered |
| D．is going to consider |
The first use of atomic weapons was in 1945, and their power __________ increased enormously eversince.
| A．is |
| B．was |
| C．has been |
| D．had been |
I__________ letters this morning and I__________ for four hours so far.
| A．will write; wrote |
| B．have written; have written |
| C．was writing; wrote |
| D．have been writing; have written |
They __________ on the program for almost one week before I joined them, and now we __________ it as no good results have come out so far.
| A．had been working; are still working |
| B．had worked; were still working |
| C．have been working; have worked |
| D．have worked; are still working |
—Hi, Tracy, you look tired.
—I am tired. I__________ the living room all day.
| A．painted |
| B．had painted |
| C．have been painting |
| D．have painted |