1.沒錯,又是所謂的狀語從句的省略或非謂語從句語法：當(dāng)狀語從句的主語為it或和主句主語相同時,且從句的謂語以be動詞開頭,則可以省略狀語從句的主語和be動詞.
即：when taken = when (the drug) is taken
2.to be discussed是不定式的被動結(jié)構(gòu),做后置定語,修飾the problems.
the problems to be discussed意思是“將要被討論的問題”.
另附三種后置定語形式如下：
被修飾詞 + to be done“將要被...的...”,如：the meeting to be held 將要被舉行的會議；
被修飾詞 + being done “正在被...的...”,如：the meeting being held 正在舉行的會議
被修飾詞 + done “已經(jīng)被...的...”,如：the meeting held 已經(jīng)舉行了的會議