Palmer, the British applied linguist, produced a guide to the English vocabulary needed for teaching English as a foreign language. The words are chosen for the following criteria EXCEPT______.

A．they are the words most frequently used by people whose native language is English

B．they include words useful to build other words

C．they include all the structural words

D．they include all the descriptive words

患儿，女，5岁。2岁时发现内斜视。检查：视力右眼0.3，左眼0.1。眼位：左眼+15°。眼球运动各方向均不受限。眼底未发现明显异常。同视机检查不合作。睫状肌麻痹下验光结果为中度远视。

为观察眼位变化情况，至少戴镜多长时间（）

A.1个月

B.2个月

C.3个月

D.3～6个月

E.1年