Mum left her son ____ just now.

Just as sound travels through the air in waves, electricity travels through the air in ______ radio waves.

Simon is looking forward to _________ the football match between China and Brazil on TV this evening.

I hear there will be _____talk on English study tomorrow morning—Do you mean ____ speech our teacherasked us to listen to

Don’t run through the red light. That’s________the traffic law.— OK，I won’t.