China is expected to export 1 billion mobile phones this year, ________ by a surge in demand for smartphones worldwide.
27. You should write the first letter of the sentence _____ capital one.
26. I called _____ you last night, but you were out.
25. The train leaves at 6:00 p.m., so I have to be at the station ____ 5:40 p.m. at the least.
24. --- How did you go to work yesterday? --- I went to work _____ my friend’s private car.
23. It is said that a bridge is being built _____ the river.