未知题型 大型设备的选择应遵循具有一定经营规模（塔吊出厂年限不得超过5年，施工电梯出厂年限不得超过4年）和服务能力（）

单项选择题 柴油机的实际循环与理论循环相比，实际循环热效率较低是由于存在（）所引起的。

单项选择题 2. Some of the sentences and phrases can never be translated literally, because______. A. there is no one to one match B. language structures are different. C. we don’t have enough vocabulary. D. English is difficult. A、there is no one to one matchB、language structures are differentC、we don’t have enough vocabularyD、English is difficult