Color-blind people often find it difficult to _____between blue and green.

As we all know, _________ car is becoming _________ popular way of transportation in big cities.

Do you spend a lot of time____ computer—No, but I spend much time_____ doing my homework.

ProfessorWilliams keeps telling his students that the future tothe well-educated.

．—Let’s throw a surprise party for mom’s 50th birthday.—That’s a good ideaWe_________several of her friends