单项选择题
During a period of “whiteout”，you should expect which of the following?（）
A.Snowfall or blowing snow B.Lack of ability to estimate distance C.Harsh contrast between sun-illuminated snow cover and the background D.Hazy horizons with extensive mirage effects
单项选择题 Don’t（） this news to the public until we give you the go-ahead.
单项选择题 Don’t（）things too seriously.
单项选择题 Do you understand（）I said?
