_____________ birthday to you! [ ]
A. happy
B. Happy
C. How
答案:B
下列说法正确的是[ ]
A.一个数的绝对值一定是正数
B.有理数可以分为正有理数和负有理数
C.互为相反数的两个数的立方仍互为相反数
D.正数的倒数是正数,负数的倒数是负数,任何数都有倒数
It never _____ humans until the mid1990s that some animals can be cloned.
A.occur
B.is occurred
C.occurred to
D.occurred