关于膳食调查时间说法正确的是()。
A.至少应在春、秋进行两次以反映季节特点
B.每次不少于7天
C.每次调查不应包括周末
D.节假日期间可进行调查
E.以上均错
参考答案:A
David's first novel, based on his experience as ______ lawyer, became _____best seller in Australia. [ ]
A. a; a
B. 不填; a
C. a; the
D. 不填; the
可控硅内部有()个PN结。
A.一
B.二
C.三
D.四