【简答题】______(我正要打电话给他)when his letter arrived.
【单选题】It worried me that the letter had not arrived, especially ________ it had never happened before.
【判断题】74LS161是集成四位二进制也就是十六进制加法计数器。
【单选题】My letter arrived shortly after he passed away. I regret _________ earlier.
A.
not to have written it
【单选题】The letter they looked forward to______ at last.
【单选题】Your letter arrived a few days ago and I must confess that this obligation completely ()my mind.
【简答题】词汇应用。 I received a letter yesterday. It 1 (write) by my sister. She 2 (stay) in Shanghai now. She is a writer. She 3 (work) for a newspaper and also writes books. She 4 (live) there for nearly a year....
【单选题】关于细胞凋亡与细胞坏死,下列说法正确的是 [ ]
C.
细胞凋亡受到严格的由遗传机制决定的程序性调控
D.
细胞的自然更新属于凋亡,被病原体感染细胞的清除属于细胞坏死
【单选题】My letter arrived shortly after he passed away. I regret ______________ earlier.