Scientists said the smaller the airborne particles, the more ______ they are to cause illness.

Old-fashioned phones matter when wireless networks _____ in disasters.

—I heard that Mary had ________ with her friend. —Really? No wonder they don’t speak to each other any longer.

–Do you need any help, Lucy?--Yes. The job is        I could do myself.

 I ________ use a clock to wake me up because at six o'clock each morning the train comes by my house.(2012·新课标全国)