Cancer should be suspected in persons who have any of the symptoms and signs for unaccountable causes and for an unreasonable period of time. 如果病人具有任何這些癥狀和表征，病因又難以說(shuō)明，而且持續時(shí)間又很長(cháng)，就應該懷疑患有癌癥。
If the scholastic achievement of highly intelligent children remains below average for an extended period, many teachers will fail to recognize their potential. 如果才智高的兒童的學(xué)習成績(jì)在持續時(shí)間內始終低于平均水平，許多教師會(huì )不認可他們的潛力。
