用括号内所给动词的适当形式填空
Xiao Li promised to chat with me on the Internet, but so far he __________ (not do) so.
At the moment we have too much to do __________ (think) of doing anything else.
Last Friday afternoon the young man __________ (hurt) in the traffic accident which happened on the highway.
Sound __________ (travel) through air at a speed of about 340 meters per second.
Food cannot __________ (keep) properly in a fridge at an unsuitable temperature.
The snow __________ (stop) when she woke up and the sun was shining brightly.
Every one of us was excited, for in a few minutes we __________ (see) Liu Xiang appear on the sports ground.
The Women’s World Cup __________ (not begin) until 1991 when China hosted it in Guangzhou.
Understanding yourself is very important to __________ (build) self-confidence.
On Earth, gravity keeps our feet on the ground and makes anything we drop __________ (fall) towards the ground.