图是连续分裂的细胞在不同时期DNA含量的测定结果。请据图回答:
在高等植物细胞中,有丝分裂常见于根尖、芽尖等()细胞。该图表示细胞分裂了()次。
参考答案:分生区;2
咽部异物可表现为()
A.痰中带血
B.咽部有异物感
C.吞咽困难
D.呼吸困难
E.引发感染时可引起发热、乏力等全身症状
When an object is dropped, the number of feet N that it falls is given by the formula , where t is the time in seconds since it was dropped and g is 32.2, if it takes 5 seconds for the object to reach the ground, how many feet does it fall during the last 2 seconds ?()