下列各项中,没有语病的一项是( )
1947年3月,国民党集中25万兵力,向哪个解放区发动重点进攻( )
—How does your mother like your presents for Mother's Day?
—Well, ________ this sweater _____ that one is fit for her. They're too big.
限制酶a和b的识别序列和切割位点如图所示。下列有关说法错误的是( )