一、Eliza is really an expect in dancing,but___singing her per

一、Eliza is really an expect in dancing,but___singing her performance is anything but good.为什么填as long as而不填when it comes to呢?
二、—Can you attend the meeting tonight?
--No,I'll be seeing the manager about something important.
三、I will employ the man __ they say is a fluent speaker of English.为何填that而不是who或whom呢?
四、“Did you see any foreigner present at the party?”"He was the only foreigner__ I saw at the party."为什么填that而不是whom或who呢?春节快乐!

一.as long as 有两个意思：（1）只要,在.的时候.（2）长（远,久）达.when it coms to 的意思有：1.当提到……；当谈到……；一谈到……；当说到……；当涉及到…….这里强调语境,“只要是与唱有关的她都不行”与前一句“表演得好”形成对比,如果没有第一句,两个都可以,但关联前一句,as long as
二.不了,由于一些要事我要去见经理.
三.本人查了很多资料,认为that和who都可以,但不能用whom,whom是宾格,因为先行词the man 同时做主句的宾语和从句的主语,只能用主格.
四.当先行词被the last ,the very 和the only修饰时,只能用that.
另外,我给你付一些只能用that的例子（网上搜的,个人举得比较全）,供你参考：1.在1.there + be 的句型中,句子的主语是先行词,而且又是物.
There are two novels that I want to read.我要读的有两本小说.
There is no work that can be done now.没有什么工作现在能做的了.
2.当先行词为主句的表语或者关系代词为从句的表语时.
This is the book that was bought yesterday.这就是昨天买的书.
Our school is no longer the school that it used to be.我们的学校不再是以前的学校了.
3.以Here is (are)开头的句子时.
Here is a film that will move anyone.这是一部将使任何人受感动的电影.
Here are two books that I will buy.这是我要买的两本书.
4.It is (high)time +定语从句中.
It is time that we should have a rest.我们应该休息了.
It is high time that they started out.他们该动身了.
5.当先行词是way等词时,关系代词用that或者in which在定语从句中作方式状语时,在口语中,常可省略.
This is the way that my father did this work.这就是我父亲做此工作的方式.
She admired the way in which I answered the questions.她羡慕我回答问题的方式.
6.在双重限定性定语从句中,如果一个从句用who或者which引导时,那么另一个从句用that引导.
He is the student that I have ever see who can jump highest.他是我曾经看到过跳得最高的学生.
My brother studies in the school which is the most beautiful in our city that isn't far from here.我的弟弟在我们的城市最美丽的学校读书,并且离这儿不远.
7.当先行词被the last ,the very 和the only修饰时.
This is the very pen that I am looking for.这正是我找的钢笔.
The only book I want to read is missing.我唯一想看的书不见了.
8.在强调句子中,并且以who ,which,what开头时.
Who was it that was lost 究竟是谁迷路了?（此句中,最好不用who来代替that,避免重复.）
What was it that you did last week?你上周究竟做什么了?
9.当先行词有序数词时.
You are the first person that I want to ask for.你是我要见的第一个人.
This is the second book that I have ever written.这是我写的第二本书.
10.当先行词被all,every,no ,some,few ,little,much,both等修饰时,
This is all that I want to say at the meeting.这就是我在会上要说的.
Have you any books that are worth reading?你有值的看的书吗?
11.当先行词既指人又指物时.
The professor and his achievement that I heard about are admired by them .我听说的那位教授和他的成就得到他们的赞美.
Let's talk about the persons and the things that we can remember.让我们谈论能够想起的人和事.
12.当先行词为anything、everything、nothing时,关系代词用that,不用which；但用something时,用which或者that均可.
Everything we have seen in China is moving.我们在中国看见的东西件件感人.
I have nothing that is worth reading.我没有什么值得一读的东西.
13.当先行词是疑问代词who时.
Who that you have ever seen can beat him in chess?你曾见过谁能在棋艺上打败他?
ps:我是外语系英语专业的,有问题可以问我.