Under the tree, ______ a black bike. [ ]
A. has
B. have
C. there is
D. there has
答案:C
用于眼底检查的快速短效扩瞳药
A.去氧肾上腺素B.多巴胺C.麻黄碱D.去甲肾上腺素E.肾上腺素
金属材料软,说明其变形抗力小,塑性好。()