设二元函数[*]则fxy(0，0)=______．
参考答案：-1
解析：当[*]，并且 [*]
—You don't look well, Don! You'd better see your doctor.
—I ________, but he said there was nothing wrong. [ ]
A. will
B. would
C. had
D. have
为满足填方工程施工质量要求，填土的有机质含量应控制为( )。
A．≤5% B．≤10% C．≥5% D．≥10%
