支水准路线应沿同一路线进行往测和返测。从理论上往测与返测的高差总和应是（ ）。
aFree shipping within the US, excellent condition, Kodak Jr. Six-16. Only notable "wear" on this camera are the initials W.M.C scratched on one side on the metal and H.E.H. on the other side. Only significant "tear" is that the seam is gone from the handle, but this can easily...
对于“发动机对点火系的要求”来说,下列说法哪一个是错误 ( )。Which of the following statements is incorrect for "engine requirements for ignition systems" ()? A、当发动机的工况发生变化时,点火提前角要随之变化When the engine condition changes, the ign