正常情况下，远近不同的物体均成像于视网膜上，这是因为图中哪一结构的调节作用？
A．①
B．②
C．③
D．④
答案：A
The very idea_________a man can think of driving in such a state is really unthinkable.
A．which
B．if
C．what
D．that
逻辑单元号
