Attempts have been made for nearly three decades to increase the amount of precipitation from clouds by seeding them with salt or silver iodide.

单项选择题The Group of Seven, a clique of Canadian artists painting at the turn of the century, has been credited with arousing a widespread awareness of Canada’s rugged landscape.

单项选择题A gift to the United States from France, the Statue of Liberty was assembled and dedicated in 1886.

单项选择题Eleanor Roosevelt urged legislation to assist the poor and oppressed.

单项选择题Acetate is one of the most important artificial fibers.

单项选择题New England town meetings, in their most highly developed form, are assemblies of the voters.