`18,` He _____________ safety goggles, but he wasn't and, as a result, the hot steel badly damaged his eyes. A. could have been wearing B. must have been wearing C. should be wearing D. ought to have been wearing

He _____________ safety goggles, but he wasn't and, as a result, the hot steel badly damaged his eyes.

A. could have been wearing

B. must have been wearing

C. should be wearing

D. ought to have been wearing

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D. ought to have been wearing có nghĩa là "nên đã đang mặc". Đây là một cấu trúc thì quá khứ hoàn thành của "ought to wear" (nên mặc). Cấu trúc này được sử dụng để diễn tả một hành động nên đã xảy ra trong quá khứ, nhưng thực tế không xảy ra.