Add proper quantifiers in brackets to make the following layout effective.

1 (combination)+1 (combination) = 1 (combination)

4 (cm) +6 (cm) = 1 (decimeter)

2 (month)+1 (month) = 1 (quarter)

5 (piece) +7 (piece) = 1 (dozen)

3 (days) +4 (days) = 1 (weeks)

6 (solar terms)+18 (solar terms) = 1 (year)