题目

当时，______，______ . 答案：【答案】4 【解析】根据集合相等的含义和集合中元素具有无序性的特点结合已知即可求解.，，故答案为：4，_____ with terror, the dog hid himself in a small cave, _____ his tail to the rain.A．Trembling; exposedB．Trembled; exposedC．Tremble; exposedD．Trembling; exposing