—When Tom got to the examination room, he realized he his pen at home.－Oh, he is too care

—When Tom got to the examination room, he realized he his pen at home.
－Oh, he is too careless.
A. had left　 　
B. had forgotten
C. was leaving　　
D. leaves

(答案→)A. had left　 　B. had forgottenC. was leaving　　D. leaves解析：句意：当汤姆到达考场时，他才意识到他把钢笔忘在家里面了。——哦，他太粗心了。结合语境可知上文描述的是一直持续到过去某时的动作，故用过去完成时态。Forget只脑海中忘记了某事；leave指的是实际上的遗弃，丢下的意思。结合语境可知选A。

这个答案应该是对的