I

• I have often come up against the problem of trying to explain that ...

• Here again one is up against the thermal problems of laser experiments.

II

• When the atoms encounter the walls of the cell they exchange energy with the walls.

• When this electron strikes (or collides with, or impinges on) an atom, ...

см. тж. со временем

• Such experiments will become more precise and more numerous as time passes.

• Since all machines wear, their defects worsen as time goes on (or by).

• Such optical binaries (stars) can be distinguished from real couples only in the course of time.

• In (or With) time some of these bacteria developed metabolic pathways that led to ...

• As time elapses, the concentration profiles take on a different shape.

• Over the years the electronic micrometer instruments have become more and more automatic.

• The magnetic poles of the Earth tend to move slowly with the passage of time.

• These substances have accumulated through time.

• The pole of relative rotation can change its position through time.

• These properties vary with time.