I don't know it.What was he doing last night?(合并为一句） I don't know what last night.

I don't know it.What was he doing last night?(合并为一句） I don't know what last night.
I don't know it.What was he doing last night?(合并为一句） I don't know what last night.

I don't know it.What was he doing last night?(合并为一句） I don't know what last night.
I don't know what he was doing last night.
我不知道他昨晚在干什么