这两句话是从句吗？？给解释一下

第一个是简单句,第二个是宾语从句.
例如：Please tell me where is the nearest postoffice?
I don't know what you want .

what are the colours of the traffic light ？
=what colour is the traffic light ？

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才看清楚,第一个句子不是宾语从句,是简单句,动词不定式作宾语,但是可以改成宾语从句:

They don't know what to do .
=They don't know what they should do .
(当主句和从句主语一致时,可以用"疑问词+动词不定式"代替WHAT引导的宾语从句.)
原句句子成分如下:
They( 主)don't know (谓)what to do(宾) .
改写的句子中
They don't know what they should do .
They don't know是主句部分,主谓宾和单句中一样; what they should do 是宾语从句部分,其中what就是连接词,不能省,在宾语从句中它又是 do 的宾语,they是主语,should do 是谓语.

第二个是复合句中的宾语从句,省略了连接词that,现在补充在括号里,that之前是主句,之后是从句.

I tell you(that) I can make you say "white".
主句的"主\谓\宾"分别是"I \tell\ you",宾语从句的句子成份是:
I(主) can make (谓)you (宾)say "white"(宾补).

是从句 宾语从句
其他例子:
Do you