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.
以下各种物质中由人体的内分泌腺产生的是（ ）
（Ⅰ） 当k=0时，求f（x）的极值；
（Ⅱ） 若对于任意的x∈0，+∞），f（x）≥1恒成立，求k的取值范围．
— My father often stops me from _______ in the river alone.
— He's right. It's too dangerous.
