秦国成为战国七雄中实力最强的国家，其主要原因是(      )

关于我国南方地区和北方地区的差别的叙述，错误的是（    ）

⑴What is this? ____           A. Thursday.

⑵What are these?____        B. Yes, it is.

⑶What is she wearing?____   C. They're shorts.

⑷Is this a new cap?____      D. She is wearing a blue skirt.

⑸What day is today?____     E. It's a new T-­shirt.

____×6＜12

____×6＜15

____×6＜22

____×6＜30

____×6＜40

____×6＜45

下列关于牛体外受精及胚胎工厂化生产的叙述中，正确的是（　　）