小儿上呼吸道感染常见夹惊的原因是（）
A．肺常不足
B．脾常不足
C．肝常有余
D．肾常虚
E．肺脏娇嫩
参考答案：C
(2013·高考新课标全国卷Ⅱ)Since nobody gave him any help，he________have done the research on his own.
A．can
B．must
C．would
D．need
American Indians________about five percent of the US population.[ ]
A．fill up
B．bring up
C．make up
D．set up
