Scientists have found _____for oil as fuel. Coal, natural gas, solar power, nuclear power and even water can replace it as sources of energy.
I just pretended nobody was at home,so I didn’t ask who ________ was.
I don’t think ________ possible to master a foreign language without much memory work.
I just choose a simpler lifestyle,________ where I can ride my bike all over and do not have to make a great living to survive.
I spent the whole day repairing the motorbike.The work was ________ simple.
The factory produced many famous cars,none of ________ shipped to foreign countries.