What is the weather system control in Yanliang from July to August?

A, China is mainly controlled by Asian high pressure in winter, which does not conform to the meaning of the question;

B, the "summer drought" weather in the eastern region is mainly formed under the control of the Pacific subtropical high, so it is correct;

C, the impact of tropical cyclones on China is mainly typhoons in summer and autumn, so it does not meet the meaning of the question;

D. under the influence of the southeast monsoon, the eastern region should be hot and rainy, so it doesn't meet the question.

So choose: B.