1 you should speed up/slow down
2 speed up your progress, or we won'tcomplete on time.
3 he speeds down.
4 he is constantly improving the speed, whichis very dangerous
5 aircraft was ascending higher andhigher/fly lower and lower
6 he increases /reduces the flight height
Speed up / slow down
You should speed up the progress of your work, otherwise we won't be able to finish on time.
He put the speed down.
He continued to improve the speed, it is very dangerous
The plane is flying high / flying low.
He increased / decreased flight altitude
1.speed up/slow down
speed up / slow down
you should speed up your work ,or you will not finish it on time .
he slowed down his car .
he kept speeding up his car ,which was dangerous
the plane flew higher and higher / lower and lower .
he raised / lowered hight of the flight .