工程项目管理层次包括:①操作层;②协调层;③决策层;④执行层。按从上到下排序正确的是()。
A.③-④-②-①
B.③-②-④-①
C.④-①-②-③
D.①-②-④-③
参考答案:B
1 lost _____pen he gave me yesterday, but now I've bought ______new one.
A. a, the B. the, a C. a, a
A.mgtgθ
B.mgsinθ
C.μmg
D.μmg