Using Mawhin's continuation theorem, the existence of periodic solutions for a class of nonlinear problem are first discussed, and then by using it, the problem of periodic solutions for a delayed sea-air oscillator coupling model for the ENSO is investigated. A new result on the existence of periodic solutions to the model is obtained.

Using Mawhin's continuation theorem, the existence of periodic solution for a class of nonlinear problem is discussed, and then by using it, the problem of periodic solution of drift motion of the guidance center in earth's magnetosphere electromagnetic field is investigated. A result on the existence of periodic solution to the model is obtained, and the feasibility of our result is explained.

Using Mawhin's continuation theorem, we discussed the existence of periodic solution for a class of nonlinear problem, and then investigated the problem of periodic solution of sport model of plasmas particle in the process of magnetosphere-ionosphere coupling. A result on the existence of periodic solution to the model is obtained.

No abstract