你一次提问太多，下次分成若干问题提问。

1.I have always been honest and straightforward , and it doesn't matter who it is I'm talking to.

it为形式主语，who it is (that) I'm talking to为主语从句。这是强调句型，就被强调的成分（to的宾语）提问构成特殊疑问句，再将倒装语序改为正常语序则构成名词性从句。强调句型中的that可以省略。

2.The Foreign Minister said,“_____ our hope that the two sides will work towards peace.”
A.This is         B.There is         C.That is         D.It is

it为形式主语，that引导真正主语从句。所以答案为D。our hope为确认性表语，与that从句意义相等。即A=B，B=A。

如果选that或this作主语，that从句为同位语从句，that或this就没什么可指代了，导致逻辑错误。因为that从句内容就是我们的希望。

3.—— I rang you at about ten, but there was no reply.

   ——oh, that was probably  _____ i was seeing the doctor.

A. when      B. that

选when没问题，相当于the time when; 能否用that，感觉语法形式上也没啥大的问题?

一个句子正确不仅语法形式上要正确，逻辑上也得通顺。指示代词that指代I rang you at about ten这件事。即your ringing me

Your ringing me was probably when I was seeing the doctor.

这个句子中，was为不及物动词，意为发生，when引导时间状语从句。用that从句是错误的。

4. Don't you think it necessary that he  （should ) not go to Miami but to New York?

    I agree, but the problem is   _that__  he has refused to (go to New York)

 he has refused to为不定式的省略形式。to后省略了go to New York。

凡是能接不定式作宾语的动词，都可以这样省略不定式。例如：

I can help him, but I don't want to. (省略了help him)

I wanted him to come with me, but he refused to. (省略了come with me)

--Come with me.

--I would like to, but I'm busy at the moment.