We know a lot about these early years of European settlement because most migrants ________ with their families and many of their letters still survive.

A．corresponded

B．related

C．associated

D．combined

下列微生物可以在二级生物安全实验室操作的是（）

A.埃博拉病毒、枯草杆菌、弓形虫

B.乙型肝炎病毒、沙门菌、弓形虫

C.高致病性禽流感病毒、沙门菌、弓形虫

D.埃博拉病毒、枯草杆菌、弓形虫