举一反三
- The geoid surface is treated as the surface of mean sea level, which is important for measuring elevations or heights. （ ）
- Throughout the past few centuries there ______ recorded reports of space vehicles which have visited our earth from another planet. A: have been B: are C: had been D: were
- There have been UFO reports for ______. A: 15 years B: 50 years C: six decades D: four decades
- Following reports of drug-taking at a boarding-school, several senior<br/>boys have been expelled. A: limited B: compelled C: dismissed D: kept
- Typical short reports have the following sections_______.
内容
- 0
It’s a shame _________ able to give them any advice. A: not to have been B: to have not been C: to have been not D: to not have been
- 1
Production costs of product Z vary depending on the level of activity. Costs have been recorded at various levels of activity as follows:What is the variable cost per unit?<br/>______
- 2
Production costs of product Z vary depending on the level of activity. Costs recorded at various levels of activity have been as follows:How much is the fixed cost of production?<br/>______
- 3
Oil production has been essentially ______ since 2005, and we have only another couple of years at this same sort of level of production before the demand for oil will ______ supply. A: flat, outstrip B: level, cap C: equal, tower D: even, shadow
- 4
The room is in a mess; it _____ cleaned. A: can’t have been B: shouldn’t have been C: mustn’t have been D: wouldn’t have been