7. 5 people participate in 4 groups, each group has two people, and each person must participate in at least one group. Then, the number of different groupings is
$\qquad$ kinds.
7. 135 .
5 people can form $\mathrm{C}_{5}^{2}=10$ pairs. Every 4 groups are called a grouping method. A grouping method that meets the requirement should include 5 people. Since fewer than 4 people cannot form 4 pairs, all the grouping methods that do not meet the requirement, i.e., those containing only 4 people, total $\mathrm{C}_{5}^{4} \mathrm{C}_{6}^{4}=75$ (each 4 people can form $\mathrm{C}_{4}^{2}=6$ pairs). Therefore, the number of grouping methods that meet the requirement is $\mathrm{C}_{10}^{4}-\mathrm{C}_{5}^{4} \mathrm{C}_{6}^{4}=135$.