目前关于门控心肌断层显像的采集,常用的采集矩阵为()。
A.32×32
B.64×64
C.128×128
D.256×256
E.512×512
参考答案:B
----- The windows must have taken you quite a long time that day.
----- Right. They ______ for months.
A.haven’t been cleaned
B.didn’t clean
C.hadn’t been cleaned
D.haven’t cleaned
中国的寒温性针叶林主要分布在大兴安岭北部山地和()。