In this way these insects show an efficient use of their (sound-produced) ability, (organizing) two sounds (delivered) at a high rate as one (call).

单项选择题I thought the technician was (to blame) for the (blowing) of the fuse, but I see now (how) I (was) mistaken.

单项选择题He has failed me so many times that I no longer place any ____________ on what he promises.