Scientists photographed for the first time ever _____ wild gorillas used a stick to test the depth of a pool before getting into it, according to a recent study.
第二部分:英语知识运用(共两节,满分45分) 第一节单项填空(共15小题;每小题1分,满分15分) 21. As we know, ______Potala Palace, a combination of Tibetan construction art and culture, is considered________precious treasure of China.