Question

Much time (spend) sitting at a desk, teachers

Much time (spend) sitting at a desk, teachersare generally troubled by health problem.
填什么形式?

Answer 1

应该是：
Much time (spent) sitting at a desk, teachers are generally troubled by health problem.
答案填：spent
解析：
这题考查独立主格结构。逗号后面是一个有完整主谓宾的句子，在英语里，两个完整的句子不能直接用逗号隔开，必须有连词，所以只能把逗号前面那句话变成分句。又因为time与spend是被动关系，所以填spent.
PS: 如果填is spent的话两个句子需要用连词and连接

Answer 2

Much time is spent sitting at a desk, teachers.

追答

老师们的许多时间都坐在办公桌前。