College entrance examination geography, two-choice questions about wind direction judgment and weather system

This question is a bit complicated. Let’s talk about why we choose A and C first. Because the plains of the middle and lower reaches of the Yangtze River are high pressure and the Bohai Bay is low pressure. According to the high pressure, the squeezing airflow with low pressure flows, and then the wind direction is deflected according to the geostrophic deflection force. Therefore, northward wind cannot be formed. A high-pressure ridge occurs at A. As shown in the figure, in the middle and lower reaches of the Yangtze River, only the air pressure at A is higher than the surrounding area, and the air pressure inside A is higher than outside. Therefore, the formation of a high-pressure ridge is impossible. The southwest wind is possible, but the southwest wind, that is, the northeast wind is impossible. As explained before

As shown in the second question, you can see that there is a low pressure in the Bohai Bay and the air pressure in the isobars The low pressure trough formed in the western Mongolian Plateau comes from the high pressure in Siberia, indicating that it is now around autumn or spring, and the air pressure difference between the east and west is very large. The high pressure airflow in Mongolia squeezes and flows towards the Bohai Bay, bringing the cold air from Siberia to naturally form a cold front.