редко бывает, чтобы
• It is rare for one reaction to occur (or It is seldom that one reaction should occur) to the total exclusion of the others.
Русско-английский научно-технический словарь• It is rare for one reaction to occur (or It is seldom that one reaction should occur) to the total exclusion of the others.
Русско-английский научно-технический словарь