StephenHawking believes that the earth is unlikely to be the only planet _lifehas developed gradually

_____UN report says Chinese Mobile Payments （支付）is changing _____ world .

it’s time I got down _____ my homework,but I just cto play D．to do; playing

What are you going to do this week-end —I plan ______ Mount Yunlong with my parents.

It is difficult to ____ one twin from theother. They almost don’t ____ from each other.