A_____ has taught us what atoms are made up of and how powerful the atom bomb is.
| A．seaman | B．salesman | C．naturalist | D．scientist |
Nearly all the streets are in ________lines, running from east to west. Those that run from north to south are called avenues.
| A．direct |
| B．right |
| C．straight |
| D．long |
—Hi, this way, please.
—OK. I sometimes have no sense of ________when I arrive at the crossroad.
| A．position |
| B．direction |
| C．situation |
| D．condition |
Along with the letter was his promise ________he would visit me this coming Christmas.
| A．which |
| B．that |
| C．what |
| D．whether |
I was just talking to Margaret when Jackson________.
| A．cut in |
| B．cut down |
| C．cut out |
| D．cut up |
Now many crops can be improved ________different species of plant, such as rice, wheat.
| A．by making |
| B．by crossing |
| C．by converting |
| D．by changing |