Choose the correct preposition in brackets.
1nbsp; nbsp; A new

Choose the correct preposition in brackets.
1nbsp; nbsp; A new computer-operated heating system was created in addition (with / to) the existing one.
2nbsp; nbsp; Representatives of different countries were engaged (in / to) the discussion of environmental problems.
3nbsp; nbsp; The new school rules will come (into / to) force next year.
4nbsp; nbsp; Governments of all countries must deal (with / about) environmental issues.
5nbsp; nbsp; Everybody should contribute (to / into) the solution of the problem.
6nbsp; nbsp; We cant solve the problem now (for / because) this simple reason: it requires time and investment.