题干
Stop cutting trees, _______ the earth will become worse and worse.
A：and
B：then
C：because
D：or
答案(点此获取答案解析）
D
Stop cutting trees, _______ the earth will become worse and worse.
A：and
B：then
C：because
D：or
，后代出现有色籽粒与无色籽粒的比是1：3，对这种杂交现象的推测不确切的是（ ）