_____ Tom _____dumplings before?[ ]
A. Did…make
B. Does…make
C. Is…making
D. Has…made
答案:D
想一想,______里填几?
298×______≈1500
509×______≈3500
______×984≈8000
38×______≈200
______×107≈800
______×62≈360.
青春前期牙周炎的特点是
A.周缘血单核细胞功能增强B.牙周破坏速度慢C.除累及乳牙外,恒牙也可受累D.牙龈炎症程度轻E.易于治愈