A：he could not do any better
B：and he could not do any better
C：so he could not do any better
D：but he could not do any better
撒哈拉以南的非洲经济落后的根本原因是（ ）
山坡羊·潼关怀古
张养浩
峰峦如聚，波涛如怒，山河表里潼关路。
望西都，意踌躇。伤心秦汉经行处，宫阙万间都做了土。
兴，百姓苦；亡，百姓苦！
