In the last decade, disasters have become increasingly common. It’s high time that we ______these issues more seriously.
—Can Professor Li be in the laboratory?—He ______ be; I saw him there half an hour ago.
My newly-purchased magazine is nowhere to be found. ______ I have left it on the train?
—Did your mother sleep well last night?—She ______ have slept through all those noises.
Don't use water to put out the fire if oil catches fire. As is known, oil ______ float on water.
—Lisa is going traveling at the cost of losing her job.—Really? She ______ a lot of money.