【判断题】过冷度越大,纯金属结晶中的临界形核尺寸越小。
【单选题】He is busy. He keeps ____ these days. [ ]
【单选题】— I think your father is very busy. —So he is._______ he still takes a walk with us sometimes.
【单选题】—I think your father is very busy. —So he is. _______ he still takes a walk with us sometimes. [ ]
【单选题】当三相交流电源发生断相情况时下面()器件会进行保护。