⑴____A. house B. mouth
⑵____A. living room B. time
⑶____A. cow B. show
⑷____A. floor B. door
⑸____A. make B. bathroom
(Ⅰ)求角B;
(Ⅱ)若 b=13,a+c=4 ,求△ABC的面积.
对图示三种活细胞共性的描述,不正确的是( )