Natural disasters occur at ________ times, so it is always difficult to warn people in advance.

________ from endless homework on weekends, the students now find their own activities, suchas taking a ride together to watch the sunrise[ ]

Sandy sits between ______ and ______ .

ied________to persuade his friends totravel with him, so he traveled alone．

My computer began to return to the ______ running state after I killed the virus by newly-updated Kaspersky.