函数在某点连续是该函数在此点有定义的( ).
A. 必要条件
B. 充分必要条件
C. 充分条件
D. 无关条件
一切初等函数在其定义域内均是连续的。 ( )
A. 对
B. 错
Jack is the only one of the classmates who ______ invited.
A. has
B. have
C. is
D. are
Is this book ______ I bought for you the day before yesterday?
A. which
B. that
C. ×
D. the one
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