用支出法计算GDP的公式可以表示为：GDP=C+I+G+(X-M)( )
参考答案：对
The affective filter hypothesis of Krashen's Monitor Model states that acquirers with （） affective filter seek and receive more comprehensible input.
A. low
B. average
C. high
D. very high
如果调查前的样本容量为800，其回答率为80%，则应抽取的样本容量为（）。
A.100
B.1000
C.640
D.6400
