One of the most important questions they had to consider was__________ of public health
—Where have you been all day?—I _______ some former classmates and I couldn’t get back until it was dark.
The process of producing electricity may also give out CO2, _______ you heat your house with electricity instead of charcoal.
—How much of the foreign expert’s speech have you understood?—Next to nothing. I wish I _______ harder at English.
Don’t refer to the dictionary every time you come across a new word as sometimes its meaning may be _______ clearly in a given context.
The Expo site should be _______ from anywhere in the city of Shanghai within 90 minutes by bus, subways and special taxis.