Correct the mistakes in the sentences (Sửa những lỗi sai trong câu) 1. You must to have a medical certificate. 2. He should works harder. 3. We should not to camp near a river. 4. They don’t must take their dog.

Correct the mistakes in the sentences (Sửa những lỗi sai trong câu)

1. You must to have a medical certificate.

2. He should works harder.

3. We should not to camp near a river.

4. They don’t must take their dog.