下列哪种检查方法不能用于遗传筛查()。
A.羊水检查
B.B型超声检查
C.羊膜镜检查
D.磁共振成像
E.绒毛活检
参考答案:C
化简并求值:(-3x2-4y)-(2x2-5y+6)+(x2-5y-1),其中 x=-3 ,y=-1。
用所给单词的适当形式填空。
1. She is _____________(自信) of passing the exam.
2. I've _____________ (认识到) the importance of learning English.
3. Many ____________(摄影师) are having a meeting here.
4. It is _____________(方便) to go to school by bike.
5. We'll go to the Great Wall, __________(包括) you.