Bạn hãy điền động từ "to be " thích hợp để hoàn thành những câu sau :
1. We are school children . We ........................ thirteen years old .
2. " How ................... you, John ? " - " I ............................. fme, thanks . "
3. Those new desks ....................... in their classroom .
4. My mother ..................... cooking the meal in the kitchen now .
5. The students ..................... camping yesterday so today they .................... tired .
