在“观察叶片的结构”实验里，徒手切片的过程中，每切一次叶片，刀片都要蘸一下水。蘸水的目的是（　　）

计算：$\sqrt{3}·\sqrt{5}$=____．

根据课文和首字母填空。
    Sandy and Sue are in a shop. They want to buy two p____ of sweets，but they are one shilling e____. That's all their p____ money. At last, they buy two small lollipops i____.
    In the afternoon, Sandy and Sue come back home from school. Tea's r____. Sandy and Sue are very h____, but Sandy's hands are very d____. Mother asks Sandy to go and w____ his hands at o____. Now Sandy's hands are clean. Look at Mum's nice clean t____! Sandy cleans his hands with it.
    On Sunday, Sue and Mum are going shopping. Mum sees a pair of nice s____, so she wants Sue to t____ them on. They are very t____ for Sue. Sue wants the pink ones and she thinks they're very p____. They're j____ right.

下列关于有机物的说法正确的是

下列各式中，计算结果是x²+7x﹣18的是（  ）