下列说法正确的是（ ） A．从空气中分离出氧气后余下的全部为氮气． B．氢气燃

用所给词的适当形式填空。

1. He _____ (go) to school by dike every morning. But this morning he _____ (go) by bus.

2. "Do you like _____ (drink) tea?""Yes,I do."

3. I'm sorry. I can't. I have to _____ (help) my mom.

4. There _____  (not be) any bread at home yesterday.

5. Tom _____ (have) no time last Sunday. He _____ (visit) his friends next Sunday.

6. Please tell him _____ (wash) his hands before supper.

7. The bus _____ (stop) already. Let's get off.

8. Doing morning exercises _____ (be) good for you.

9.  Tom's brother _____ (be) good at soccer.

10.  Finally he asked people to stop _____ (talk).

小刚同学绘制了如图所示 A，B 两种固体物质的溶解度曲线．

（1）温度为t₁℃时，A物质与B物质的溶解度______（填“相等”、“不相等”或“不能比较”）．

（2）将A物质t₂℃时的饱和溶液降低温度至t₁℃时，其溶质质量分数______（填“变大”、“变小”、“不变”）．

在我国进出口贸易中，若按FAS术语成交，下面说法错误的是（）。

A．卖方要在约定时间内将合同规定货物交到指定装运港买方所指派船只的船边

B．若买方所派船只不能靠岸，卖方要负责用驳船把货物运至船边，仍在船边交货

C．装船的责任和费用由买方承担

D．在船上完成交货义务

一套加氢裂化装置从规划到正式投产，关于其中间环节准备工作分几个阶段，下列说法不正确的是（）。

A.设计

B.建设

C.开工

D.验收