David had to __________the invitation to the party last weekend because he wasn't free（ ）
A．turn onB．turn downC．turn upD．turn off
____my grandpa is over 80 years old， he still looks strong and healthy．（ ）
A．AlthoughB．BecauseC．Unless
Be more____next time， and you won't make the same mistake again．（ ）
A．carelessB．carefulC．nervous
This is a really old bike．
Yes，I____it for seven years．（ ）
A．have hadB．have bought
C．Bought
How is your friend going to the station？
I'm not sure． He____take a taxi there．（ ）
A．mustB．has toC．may
The relations between my parents have become difficult． What should I do？
You could do more jobs around the house so that they have more time for proper____．（ ）
A．instrumentB．communication
C．community