在农药管理中处于核心地位的是( )
A．《农药安全使用规定》 B．《农药生产管理办法》C．《农药管理条例》 D．《农药登记规定》
参考答案：C
“Was his father very strict with him when he was at school?” “Yes. He had never praised him _______ he became one of the top students in his grade.”
A．after
B．unless
C．until
D．when
下面两个语句的区别在于Xl不能多次赋值，而X2可以______赋值。 X1 EQU 1000 X2=1000H
