4x(x-2019)-x+2019=0 Tìm x:

Mọi người giúp em câu b bài 16 với ạ

11. They are hard workers.

=>They..................................................

12.Nam speaks English fluently.

=>Nam is...................................................

13.Lan is a poor student, but she studies very well.

=>Although...........................................

15.There are 30 rooms in my shool.

=>My school's .......................................

16. My house hasn't got a garden.

=>There is.............................................................

17.It is an interesting film.

=>what.....................................................................

18.Ther weather was very hot , so we went swimming.

=> Because...............................................................

19.When the phone rang, we were having dinner.

=> While...................................................................

20.She had an accident while she was climbing.

=> she was........................................................................ 

3.Photographers need to think creatively to take good photos.

=>photographes think..................................

4.You need to wait for a long time.

=>You need to...................................................

5.Photographers also neen to sit quietly.

=>Photographers should find a.....................................

6.Ms Lan is a good teacher.

=>Ms Lan.......................

7.She is a safe cyclist.

=> She.........................................

8.My father doesn't drive carelessly.

=>my father is................................

9.quang Hai plays soccer skilfully.

=>Quang Hai is.............................................................

10.She runs very slowly.

=>She is.......................................................................

Kim loại R có hóa trị 3. Hợp chất tạo bởi R và nhóm SO₄ có phân tử khối là 400 đvC. Hãy xác định nguyên tử khối của R