A number of trees have been planted ________there was nothin

A number of theories have been proposed to explain the situation.

A:suggested
B:tested
C:used
D:announced

If you have never planted anything, you won’t be able to know the pleasure of watching the thing you have planted_______.

A.grow
B.to grow
C.growing
D.to be growing

共用题干
We Need Green Space

Decades ago,any open field,any vacant lot,any group of trees were the places where children played.As families left family farms,small towns,and the countryside,and moved into cities,the places for their children to play in became rarer.(46)_________
In fact,all people's lives change a lot when they move to the city. In cities,homes are built on top of one another in enormous apartment buildings.The feeling of private space and ownership no longer exists in houses literally piled one on the other.
Psychologists have been studying the changes people experience when they leave rural areas and move into urban environments.(47)________Children can play on paved playgrounds.That's true.(48)_________Without grass and trees and bushes and,yes,dirt and mud to get dirty in, children miss an important part of childhood.The human soul,it seems,needs to stay close to its roots.
Adults can plant lots of things like bulbs in window boxes and large containers.(49)_________ The lack of green space is now recognized and understood as a problem.
City planners一the people who design neighborhoods一have begun to work on a solution.They want to build more parks,but land in cities is quite costly.So they look for land that no one else wants.Along rivers,under power lines,near ditches and highways—(50)________Why not use these unused spaces for green areas?Neighborhood groups have coordinated their efforts to clean up the trash or garbage.Soil from new building projects in the city has been trucked by lorries into these areas.This soil has been dumped along the sides of rivers,and strong walls have been erected to hold it there.Trees and bushes have been planted;the roots of these plants will hold the soil, too,and the green leaves make the area beautiful.

________（49）
A:However,they just don't have as much fun as children in small towns.
B:Children in the cities had few options,fewer choices of places to play.
C:Why is there no place children in cities to play?
D:One clear finding from their studies is that people need green spaces for better mental health.
E:However,tending window boxes isn't the same as being an amateur gardener and growing peas,tomatoes and salad greens in a backyard garden.
F:these are the spaces that no one uses and they are everywhere.

The number of foreign students attending Chinese universities __________ rising steadily in the past ten years.

A.was
B.were
C.has been
D.have been