24. After ______ seemed a long time, Mr. Li stood up and broke the silence.
Television has many advantages. It keeps us ____ about the ___ news and also provides entertainment in the house.
Is there a certain cure ___ lung cancer yet?
-- Can I call you back at two o'clock this afternoon? -- I'm sorry, but by then I ____ to Beijing. How about five?
The little boy was allowed to go to have a swim _____ he finished his homework.
-- Can you keep an eye on my bag? I need to go to the washing closet. -- ________ . It'll be safe with me.