下列过程使物体质量发生变化的是（） A．一块冰化成水 B_爱下问搜题

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问题选择题

下列过程使物体质量发生变化的是（　　）

A．一块冰化成水

B．将月球上的一块矿石运回到地球

C．将一铁块烧红

D．将铁杵磨成针

答案

A、冰熔化成水，是状态发生了变化，质量不会改变．故A不符合题意．

B、将月球上的一块矿石运回到地球，物体从月球到地球只是改变了位置，质量不变．故B不符合题意．

C、将一铁块烧红，只是铁的温度变了，但是其质量不变．故C不符合题意．

D、将铁杵磨成针，物体所含物质的多少变了，即减少了．故物体的质量变了．故D符合题意．

故选D．

完形填空

阅读下面短文，按照句子结构的语法性和上下文连贯的要求，在空格处填入一个适当的词或使用括号中词语的正确形式填空，并将【【答案】】填写在答题卷标号为16-25的相应位置上。

Vitamins are complex chemical substances 16 (find) in many foods. The human body needs them for health and 17 (grow). The body makes some vitamins, 18 usually in amounts too small to meet its needs. 19 vitamins are not made in the body. These must be supplied. No one knows exactly 20 all vitamins work. Doctors 21 know that vitamins have very special uses. One vitamin 22 cannot take the place of another. The steady absence of one vitamin in 23 otherwise complete diet causes a deficiency disease. Rickets, scurvy, and pellagra are examples of deficiency diseases.

It is best to obtain vitamins 24 eating the foods in which they occur. There are also pills that contain a single vitamin or a combination of vitamins. People should consult 25 doctors before they take any vitamin pills.

单项选择题

性凉，能清热化痰的药是（）

A.炉甘石

B.猫爪草

C.升药

D.硼砂

E.大蒜