If you have any questions, please feel free to interrupt at any time.  This sentence means if you have something that you don’t understand,  you can make a break in at any time.

Mr. Smith isn't available.This sentence means Mr. Smith is free and not busy. 点击查看答案&解析

Let's move from the general to the specific.This sentence means let’s talk about some particular and about some part, but not about the whole. 点击查看答案&解析