We feel ______our duty to make our country stronger and stronger.
The river smells terrible. People_______ dirty things into it .
---Miss Li, where did you visit last week? --- I visited a big company __________ ships are made.
---Mum, have you seen my mobile phone? ---_______ you bought last week? I’m afraid I haven’t seen _______.
--- Bill, can I get you anything to drink? --- _________.
---Mum, could you buy me a dress like this? --Certainly, we can buy _______ one than this, but ________ this.