With the popularity of network, email has largely ________ the traditional letter.
27. Since 1994, the glacier in Antarctica has lowered by as much as 90cm, ______________sea level to rise.
26.—Flight MU257 _______________ . I must be off now.—Have a nice trip.
25. When _______________ comes to saving energy, big changes start with small steps, like turning off the lights.
24. Of the two cameras, I would prefer _______________ one, which is very easy for me to carry.
23. Mr Jones, a professor, ___________ for his excellent lectures, is popular with his students.