—How was your summer holiday, Lily?—I went to Beijing with my parents and we _________ a good time there.
A：have
B：had
C：have had
D：will have
In addition, I gave five more dollars to her.
使用敌敌畏来防治三化螟害虫，开始效果很显著，但长期使用以后效果越来越差。原因是
