（一）
"Can I help you?"
"Thanks, but I'm already ____ "
A. helped
B. being helped
C. having helped
D. helping
答案是B，但我想问A为何不行？
查被动式只有“be + p.p.”，好像A也是合文法的？
（二）
If you are interested in knowing more, then it is pobably best to use the
sales __(3)__ form to kick things off.
A. enquiring
B. enquire
C. enquiry
D. enquirer
我想 enquiry form 是名词+名词的用法，
不过前面的sales在这里是什么意思呢？

A is semantically odd.

I’m helped.总是有人帮我。I’m being helped.现在有人帮我。

sales enquiry form是买方写给销售部门的咨询表格直接google"sales enquiry form"可知长什么样子。