breed in and in

in-and-in

swelling and pain in knee

swelling and pain in throat

difficulty and beauty expressing event-group

difficulty and challenge

difficulty and contradiction

difficulty and countermeasure

difficulty and hot spot of pharmacokinetics study

Difficulty and period

difficulty and problem

difficulty in defecation

difficulty in delivery of the fetus

difficulty in dissection

difficulty in employment

Difficulty in finding jobs

difficulty in obtaining employment

difficulty in solving questions

difficulty in starting