Take a look at the bread. I think it has been bitten. I guess there are ____ (mouse) in the kitchen.
为提高农作物的产量，提高光合作用效率，下列哪项做法是可取的？（ ）
①合理密植 ②尽量密植 ③间作套种 ④大面积单一作物种植．
