Viết lại câu sao cho nghĩa ko đổi 1. They have just sent an ambulance to the school => An ambulance ... 2. ''There are flights from Nha Trang to HN twice a week" they said to me => They told me ... 3. It's 3 years since I last saw Nam => I haven't ... 4. Keeping the environment clean is very important => It's ... 5. Learning E is very necessary => It is ... Nếu được các bạn có thể cho mk công thức đổi luôn được ko ạ ~ Thanks nhìu ạ!!!