“Sorry, sorry…”, he whispered, _______ talking to himself.
| A．while | B．even if | C．as if | D．when |
Children’s brains can’t develop properly_______ they lack protein(蛋白质).
| A．when | B．since | C．because | D．unless |
This is the very toy car ________ which he came here the other day.
| A．by | B．in | C．for | D．on |
Spacecraft “Discovery” has failed in the course of launch.
----_______? They have been preparing for the test.
| A．How come | B．When | C．How | D．Why not |
I began to fish before memory began, _______ I know I have always fished.
| A．so far | B．so as far as | C．as far as | D．so |
Elbert Einstein, for ______ life had once been very hard, was successful later in science .
| A．whom | B．whose | C．which | D．his |