A. 中性粒细胞 B. 肺泡壁上皮细胞 C. 肺泡吞噬细胞 D. 柱状上皮细胞 E. 淋巴细胞
A. 对 B. 错
A. devote yourself to singing B. take trouble to sing C. sing happily D. try your luck at singing