1. They allowed him to write a letter to his wife

allow sb to V: cho phép ai làm gì

2. She spent two hours on preparing the meal

S+ spend+ time/money+ on Ving

3. After Lan had learned her lessons, she went out for a walk

after S+ had P2, S+ Vqkđ

4. Learning English is quite easy

Ving làm chủ ngữ=> V chia số ít 

5. She is not pleased to empty the kitchen garbage

S+ tobe+ adj+ to V

6. His dog has run out of the garden for 20 minutes

for 20 minutes=> htht: S+ have/has+ P2