A correct and good light is beneficial to the production of producers, and direct sunlight is not allowed. After all, if the stability of the artificial ecological tank is low, plants and some small animals will be killed by too strong sunlight.

B wrong, the stability of artificial ecological trough depends largely on the external environment. If you put the outside world in the sun like the ordinary A option, the system will crash more easily.

C can be correct according to personal understanding.

I may not be sure about item D, but I personally think it is correct. There is no problem with its expression, but according to the practice of the ecological tank in the book, it is necessary to cover it. This is the last step, so it depends on personal understanding.

That's all I can say. Don't be surprised if you are not satisfied ~ ~