题型:选择题 I would like to speak for our group to express our ________ for your valuable help.[ ]A. agreement B. attentionC. appreciation D. anxiety 查看答案
题型:选择题 H2是最理想的能源之一,下列关于H2说法中不正确的是( )A.H2易液化,携带方便B.生产H2的原料来源广阔C.在等质量的可燃性气体中,H2燃烧时放出的热量多D.H2燃烧时无污染 查看答案