先看下面一道高考试题：
—How long are you staying?
—I don’t know. _______.（江苏2004）
A. That’s OK  B. Never mind
*C. It depends  . It doesn’t matter
解析：本题考查交际用语和惯用法。根据问句的意思“你打算呆多久？”，可知答案应为C，意思是“（我也不知道）视情况而定吧！”。

It/That(just) depends通常用于口语，意思是“看看再说；视情况而定”，在此正合题意。That’s OK主要用于对道谢和道歉的答复，意思是“没关系；别客气”；Never mind和It doesn’t matter主要用于对道歉的答复，意为“不要紧；没关系”，两者均不合语境。
再看一个句子：Future agriculture should depend on high technology as well as traditional methods.
说明：depend的意思是“依靠；依赖”，为不可数名词，后接宾语时应与on或upon连用，注意用于被动结构时，不要把on或upon漏掉了。
depend一般不用于进行时，其主要用法如下：
1. 表示“依靠；依赖；指望”，接宾语时与on或upon连用。
（1）后接名词或代词。
We shouldn’t depend on foreign countries for oil.
我们不应当依赖外国的石油。
The map is a thing to be depended on when you are in a strange place.
在陌生的地方你就得靠地图。
（2）后接带不定式的复合结构，即depend on/ upon sb. to do sth., 意思是“指望某人做某事”，可转换为depend on one(’s) doing sth.。
You can’t depend on them to do it. = You can’t depend on their/ them doing it.
你不能指望他们做这事。
（3）用于“depend on / upon it + that从句”这一结构，意思是“指望……；对……不怀疑”。
You may depend on it that they will be there in time.
你不用怀疑，他们会及时到达那里。
2. 表示“视……而定；取决于……”，也是不及物动词，后接宾语时常与on或upon连用。值得注意的是，depend on/ upon作此意解时不可用于被动结构。
（1）后接名词或代词作宾语。
The price depends on the quality.
价钱取决于质量。
（2）后接how或wh-引起的从句，在口语中可省略on或upon。
Your success depends (on) whether you work hard or not.
你的成败取决于你是否努力工作。
3. 常用短语
（1）depend upon/ on it表示“无疑地；的确”，为副词性短语，主要用于口语中，通常放在句首或句末；或用作动词性短语，表示“相信”。
Depend on it, they will pass the examination.
请放心，他们一定会通过考试的。
（2）That (all) depends = It (all) depends，意思是“这很难说；那得看情况（而定）”，主要用于口语中。
I may help you, but that/ it depends.
我也许会帮助你，但得视情况而定。

主要意思为“依靠”、“依赖”、“取决于”等，只用作不及物动词，通常与介词 on, upon 连用，主要用法有：
1. depend on [upon]＋某人或某物
Whether we’ll go camping depends on the weather. 我们是否去野营要看天气。
I haven’t got a car, so I have to depend on the buses. 我没有汽车，所以我得乘公共汽车。
有时可在某人或某物后用介词 for。如：
We depend on the radio for news. 我们靠收音机听新闻。
Children depend on their parents for food and clothing. 儿童的衣食靠父母。
2. depend on [upon]＋某人或某物＋不定式或动名词
I’m depending on you to do the work. 我指望你做这工作。
You can never depend on him [his] arriving on time. 你决不能指望他能准时到达。
You can’t depend on the train arriving on time. 千万不要认为火车能正点到达。
3. depend on [upon]＋从句
Our success depends on whether everyone works hard ornot. 我们的成功取决于每个人是否努力。
The amount you pay depends on where you live. 你付多少钱要看你住什么地方。
在 It (all) depends on [upon]＋从句中，介词 on, upon 有时可省略(主要见于口语中)。如：
It all depends how you do it. 那要看你怎么办。
It depends (on) whether you can afford it. 这要看你是否买得起。
注：depend on [upon] 后不接 that-从句(此时须用 it)。如：
You may depend on it that he will join our club. /You may
depend on him to join our club. 你可以指望他加入我们的俱乐部。
4. 口语中说 It (all) depends. /That depends. 意为“那要看情况”。如：
A:Are you going too? 你也去吗?
B:That depends. 那要看情况。
I want to leave early but it all depends. 我想早点离开，但那要看情况。

一. vt. 依靠：依赖：指望

e.g. (1)You can not depend on your parents forever.

(2)Children depend on their parents for food and clothing

常用句型: depend on sb. To do sth　等于 depend on sb./sb.’s doing sth.

e.g. (1) You can’t depend on him to come punctually.

===You can’t depend on him/ his coming punctually.

　　(2) I depend on you to do it.

== I depend on you/your doing it.

高考考点: 当其后接 that-clause时必须用it 先行,用做形式宾语,无实意.

句型为: depend on it + that-clause. 指望---./对---怀疑

e.g. (1) You may depend on it that he will join our club.

(2) You may depend on it that they will send us some food and gas.

注意: that-clause 宾语从句通常不能充当介词的宾语,(但是在个别介词

如:Except/but /beside/in等后例外)如果要接that-clause 宾语从句须it 先行.

e.g. (1) I know little about him except that he is an American.

二. 视/靠---而定；取决于

A. 常用句型: depend on + n.

　　(不用被动语态)

e.g. (1)　The price depends on the quality.

(2) Whether he can go or not depends on his parents’ wishes.

B.　Depend on + wh-clause.

(1) Our success depends on whether everyone works hard or not.

常考固定短语:a.　 That (all) depends. 等于 It (all) depends.

　(1) I may help you, but that/it (all) depends.

　(2)____Will you spend so much money on the film ticket?

　　____That depends.

　(3) Sometimes, we’re busy and sometimes we’re not. It (all) depends.

b.　depend on it.　无疑地:的确(常用于句首/句尾)

(1) Depend on it. He will pass the examination.

注意: depend on　等于　depend upon

高考联接:

例一:---How long are you staying?(2004江苏卷,35)

---I don’t know.______________.

A. That’s　OK B Never mind C. It depends D .It doesn’t matter (Key: C)

例二：＿＿How often do you eat out?(2004天津卷,21)

---________,but usually once a week.

A Have no idea B It depends C. As usual D. Generally speaking (Key: B)