Question

You don’t know about the difficulty I had ______the work then at all.

Answer 1

D
the
difficulty
in
doing
sth
可以看做是一个词组，意思做某事的难处
其中
I
had是状语修饰the
difficulty，作用就是强调我的工作很难做。做题目的时候可以把I
had拿掉
其中in+dong
sth/sth
意思在某方面
举例
the
difficulty
in
looking
for
a
job
找工作的难处

Answer 2

b
to
do
你完全不知道我当时做这工作有多困难。
the
difficulty
i
had
我面对的困难
to
do
the
work
去做这工作。