【单选题】The difference in water spray pattern between the high-velocity tip and low-velocity applicator used with the all-purpose nozzle is due to ______.
A.
a difference in water pressure
B.
the method of breaking up the water stream
C.
the length of the applicator
【简答题】下列物质中:N 2 、H 2 O、Na 2 O 2 、CaCl 2 、KOH、NaF,只含有共价键的物质是______;只含有离子键的物质是______;既含有离子键,又含有共价键的物质是______;阴、阳离子个数之比为1:1的物质是______.
【简答题】甲容器内有物质A和物质B,其质量比是2:3,乙容器内有物质B和物质C,其质量比是1:2,丙容器内有物质A和物质C.现将甲乙丙三容器中的物质以1:2:3的比例取出,混合,则所得新的混合物中,A,B,C三种物质的质量比是183:152:385.求丙容器内物质A和物质C的质量比.
【单选题】下列各组物质中,物质之间通过一步反应就能实现图示变化的是 物质编号 物质转化关系 a b c d ① FeCl 2 FeCl 3 Fe CuCl 2 ② NO NO 2 N 2 HNO 3 ③ Na 2 O Na 2 O 2 Na NaOH ④ Al 2 O 3 NaAlO 2 Al Al(OH) 3
【单选题】In the velocity parallelogram drawn based on the theorem of composition of velocities,
A.
the absolute velocity is diagonal of the parallelogram formed by the transport velocity and relative velocity.
B.
the transport velocity is diagonal of the parallelogram formed by the absolute velocity and relative velocity.
C.
the relative velocity is diagonal of the parallelogram formed by the transport velocity and absolute velocity.
D.
the algebraic sum of the projections of the absolute velocity, transport velocity and relative velocity on any axis is equal to zero.
【简答题】叙述拉乌尔定律和亨利定律的内容,并比较拉乌尔定律和亨利定律的适用条件。
【单选题】锯齿波触发电路由锯齿波产生与相位控制、( )、强触发与输出、双窄脉冲
【多选题】What is the difference between velocity and speed?
A.
Velocity is a vector, and speed is a scalar.
B.
Speed is a vector, and velocity is a scalar
C.
Speed states only a magnitude, and velocity states a magnitude and direction.
D.
Velocity states only a magnitude, and speed states a magnitude and direction.