3 câu cuối nhé thêm công thức nữa  nhé 
----- Nội dung dịch tự động từ ảnh -----
1. It is essential that Professor Van Helsing
is met at the airport.
=> Professor Van
Helsing.............
1. It is necessary that this work be finished
by Monday.
=> This work......
2. It 's necessary for you to drink enough
water every day ==> you
must.............
3. Learning English is very necessary =>It
is..............
......