单选题：Whendiddinosaursbecomeextinct?

题目内容：

Whendiddinosaursbecomeextinct? A．300millionyearsago.
B．250millionyearsago.
C．60millionyearsago.
D．65millionyearsago.

参考答案：

答案解析：

HowdidWignallcalculatethekillingpowerofthoseoldervolcaniceru

HowdidWignallcalculatethekillingpowerofthoseoldervolcaniceruptions? A．Byestimat

分类：卫生类题型：单选题

Dialogue ThreeA：It’s very late．Are you still on the computer?B：Well，yes．_____8

分类：卫生类题型：单选题

Peoplewithouthearingproblemsmayalsobeinterestedinusing__________ A．whatyousay B

分类：卫生类题型：单选题

Somechildrenhaveneverseenadentistbeforestartingschool. A．Right B．Wrong C．Notmen

分类：卫生类题型：单选题

Thestudyactuallyprovedforthefirsttimethebenefitofstemcelltherapy. A．Right B．Wro

分类：卫生类题型：单选题