Either you or one of your students _____to attend the meeting that is due tomorrow. [ ]

Inoculation(接种) of the H1N1 vaccine ___ launch another round to weak people in February,but due to a global shortage, that has not happened yet

Only when he started to explainthe reason for this.[ ]

－ ________ does the bridge made of steel weigh －About 90,000 tons.

Don’t eat________ snacks because there’s ________ sugar in them.