问题
选择题
下列各物质按照单质、氧化物、混合物的顺序排列的 [ ]
A．水银、蒸馏水、从化米酒
B．冰、干冰、冰红茶
C．氮气、沼气、空气
D．金刚石、铁矿石、生石灰
答案
答案：A
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下列各物质按照单质、氧化物、混合物的顺序排列的 [ ]
A．水银、蒸馏水、从化米酒
B．冰、干冰、冰红茶
C．氮气、沼气、空气
D．金刚石、铁矿石、生石灰
答案：A
| 综合填空：用方框中所给单词的适当形式填空，使短文正确、通顺。 | |
You should put the least stress (压力) on your 1______. If you have good posture, you won't get tired 2______ you won't get pain in your back；you will look good! When you are sitting down, ★ 3______ to keep your back straight. ★Don't cross your legs. ★Put your back 4______ the back of the chair. If you are working on a computer, ★Sit back and 5______ your arms out to the keyboard. ★Bring your 6______ up close to the keyboard so that you can rest your arms on the chair 7______ desk. Keep your shoulders 8______. ★You need to rest and move around 9______ 30 minutes to let your body relax. ★Try bending (弯) back a few 10______ to help your body relax. |