In the 1950s in the USA, most families had just one phone at home, and wireless phones _______ yet.
haven't invented
haven't been invented
hadn't invented
hadn't been invented
Not only a little girl but also adults ___ a growing appetite for junk food nowadays
All we need a small piece of land where we can plant various kinds of fruit trees throughout the growing seasons of the year.
Generally, students’ inner motivation with high expectations from others ______ essential to their development.
The university estimates that living expenses for international students ________ around $8,450 a year. which ________ a burden for some of them.
His teacher told him that since his parents were working abroad, either his grandparents or one of his uncles ______ allowed to come to the parents’ meeting .