下列动物属于益虫的是( )
A.蝗虫螳螂
B.七星瓢虫蚯蚓
C.蝉蝴蝶
D.飞蛾蜜蜂
答案:B
七星瓢虫能够捉害虫,蚯蚓能够疏松土壤,能够清理垃圾,所以七星瓢虫和蚯蚓属于益虫。
Where must the 0mster or person in charge of a ship record the date of each test of emergency lighting and power systems and the condition and performance of the equipment?()
A.On the Certificate of Inspection
B.On the Muster List ("Station Bill")
C.In the Operations Manual
D.In either the official or unofficial log
如图是在同一直线上运动的甲、乙两物体的s—t图象,则两物体()
A.在0~t1时间内都做匀速直线运动
B.在0~t1时间内运动方向相同
C.从不同的出发点同时出发
D.在t1时刻相遇,相遇后都做匀速直线运动