Dozens of scientific groups all over the world have been _____ the goal of a practical and economic way to use sunlight to split water molecules.

[单选题]Over the past century, all kinds of unfairness and discrimination have been

[单选题]Over the past century, all kinds of unfairness and discrimination have been

[单选题]Over the past century, all kinds of unfairness and discrimination have been

[单选题]Over the past century, all kinds of unfairness and discrimination have been

[单选题]Over the past century, all kinds of unfairness and discrimination have been

[单选题]A．Societies all over the world name places in similar ways. Quite often there is no official naming ceremony but places tend to be called names as points of reference by people. Then an organized body steps in and gives the place a name. Frequently i

[单选题]Passage FourStudents all over the world have to work for their education. A college education in the United States isexpensive. The costs are so high that most families begin to save for their children's education when their children are babies. Eve

[问答题]People all over the world are trying to help the people in Sichuan.

[问答题]People all over the world are trying to help the people in Sichuan.

[单选题]The news _____he had landed on the moon spread all over the world.A.whichB.