High school geography problem (first aid)! ! !

The first problem is a, because the slot line exists in low-pressure system, which is generally called low-pressure slot. Under the control of high-pressure system, the weather is sunny, under the control of low-pressure system, there is rainy weather, and rainy weather exists in low-pressure trough, so it is controlled by low pressure, the air pressure is reduced, and there is rainy weather. The second topic is D, because the low pressure centers may be A and B, so there are two situations, as shown in the figure:

The first case: when B is the center of low pressure, the cyclone in the northern hemisphere rotates counterclockwise, so the trough line ab is south, not A, so this case can be ruled out, as shown in the following figure:

In the second case, when A is the center of low pressure, the cyclone in the northern hemisphere rotates counterclockwise, so the trough line moves northward, that is, to A, which is in line with the question. At this time, the wind direction of A is southeast wind. Fig. 3 is taken from part of fig. 2, so that it can be seen more clearly, as shown in the following figure:

I hope you can understand.