人参中含有的皂苷都属于四环三萜类。

If you often have a cold, headache or backache, there is something wrong with your health. Eating healthy food 1  good for our health. .Tofu（豆腐）, milk, vegetables are healthy for us.

Tofu is a kind of traditional（传统的）   2  food. We often   3  it in China. Now more and more people   4  other countries think tofu is good for health,  5 . They also like eating it.

Milk is   6  kind of health food. Every day you should   7  one or two glasses of milk. It can   8  us strong.

Vegetables are very important. You should eat   9  them. There are vitamin(维他命) A, B, C, D , E and so on in them.

As we know, it’s important   10  a balanced diet(均衡饮食). We must have the right kinds of food. We should also eat some pork, chicken and beef. We should eat more fruit and vegetables but less meat.

(       )1 A are       B is         C will be    D was

(       )2 A Japanese  B American  C English   D Chinese

(       )3 A eat       B drink      C take     D play

(       )4 A for       B with       C in       D at

(       )5 A too       B also       C well   D either

(       )6 A the other  B other      C another  D others

(       )7 A drinking   B drink     C take     D to take

(       )8 A keep      B make    C keeps    D keeping

(       )9 A a lot       B plenty    C much    D  lots of

(       )10 A making   B to keep    C keeping   D to drink

在食物链和食物网中能量流动的方向是                         （   ）

A．单向的

B．双向的

C．循环的

D．可以重复的

通过执行Word“文件”菜单中的“关闭”命令，可以退出Word应用程序。

已知反应：X+2NaOH＝Y+Na₂CO₃，下列说法不正确的是

A．Na₂CO₃俗称纯碱

B．若Y是H₂O，则X不一定是一种盐

C．该反应一定是复分解反应

D．NaOH固体需密封保存

生活饮用水的PH值应在（）范围内。

A.5-7

B.4-5

C.6.5-8.5