_____ to nuclear radiation, even for a short time, may produce variants (变异体) of genes in bodies.
| A．Being exposed |
| B．Having exposed |
| C．Exposed |
| D．After being exposed |
–Did a letter come for me?
–Yes, ____ came for you this morning.
| A．that | B．it | C．one | D．the letter |
Jane nearly missed the flight ____ doing too much shopping.
| A．as a result of | B．on top of | C．in front of | D．in need of |
Your body language _____ your real emotion.
| A．gave in | B．gave up | C．gave away | D．gave out |
. _____, Mother will wait for him to have dinner together.
| A．However late is he | B．However he is late |
| C．However is he late | D．However late he is |
. The Roman Empire _____ for several centuries.
| A．exists | B．existed | C．was existed | D．is existing |