$1$. You mustn't use mobile phones in this museum

`->`must + (not) + V-inf: cấm làm gì

$2$. Are they going to postpone the meeting till next Tuesday ? 

`->`Thì TLG: S + be going to + V-inf

`->`Diễn tả một sự việc chắc chắn xảy ra hoặc lên kế hoạch từ trước

$3$. The words were so small that the teacher couldn't read

`->`CT "so...that" ( quá...đến nỗi ): S + be + adj + that + S + V

You are not allowed to use mobile phones in this museum. (Use modal verbs)

--> You __nustn't use mobile phones in this museum__

Must not + V-bare: cấm không đc làm gì

 Do they plan to postpone the meeting till next Tuesday?

--> Are ___they going to postpone the meeting till next Tuesday _____ ? 

Thì tương lai gần "be going to + V-bare" diễn tả hành động sắp diễn ra hoặc đã đc lên kế hoạch từ trc

The words were too small for the teacher to read.

--> The words were so __small that the teacher couldn't read__. 

Cấu trúc "so...that" (quá...đến nỗi mà): "S + be + so + adj + that + S + can/could/... +V-bare ..."