In 1850,about a third of U.S.A___(be) covered by forests.

In 1850,about a third of U.S.A___(be) covered by forests. △In1850,about a third of U.S.A.( )covered by forests.A.were 1.单选In 1850,about a third of U.S.A.______covered by forests. In 1620,about half the U.S.A.was covered by forests. 【英语】关于主谓一致△In1850，about a third of U.S.A.( )covered by fores the Great Wall in Chian will be covered by forests ( ). 英语翻译In 1620，about half the USA was covered by forests.Today 英语翻译In 1620,about half the USA was covered by forests． Today In 1620,about half the USA was covered by forests.此句子对吗? The Great Green Wall in China will be covered by forests ( ） in about a third of a About two thirds of the Earth's surface is covered by the se