下列哪些是导致中东地区冲突不断的因素：①“三洲五海之地”优越的地理位置、②丰富的石油资源、③淡水资源紧张、④民族和宗教矛盾、⑤争夺领土、河流、运河、海峡 [ ]

A、①②③④⑤

B、②③④⑤

C、②③⑤

D、②④⑤

. --- Did you often e-mail your family during the first year at university?

--- No. I was so busy meeting new people that I didn’t write to my family as I _____.

A．ought to

B．should do

C．should have written

D．should have