他们总是诚实而公平地对待客户。

They have always dealt ___honestly and fairly with their customers.

如果我们想诚实而真诚地回答这个问题，我们应该考虑把动物养在动物园里的优点和缺点。

If we want to answer [this question] ___honestly and sincerely, we should think about [the] advantages and disadvantages that keeping animals in zoos results [in].

我可以诚实地说，我已经尽力了。

I can ___honestly say I did my best.