皮皮学，免费搜题
登录
搜题
【单选题】
一个8421 BCD码计数器至少需要（）个触发器。A.
2
B.
4
C.
6
D.
8
拍照语音搜题，微信中搜索"皮皮学"使用
参考答案：
参考解析：
知识点：
皮皮学刷刷变学霸
举一反三
【单选题】Great changes _____ in our country since twenty years ago. [ ]
A.
have taken place
B.
have been taken place
C.
took place
【单选题】—How do you like China? —Great changes _______ since I _______ here 8 years ago.
A.
have taken place; came
B.
took place; have come
C.
took place; came
【单选题】Great changes ______ in China since1978.
A.
have been taken place
B.
had taken place
C.
have taken place
【单选题】Great changes______ in the city since1970.
A.
have been taken place
B.
have taken place.
C.
has taken place
D.
took place
相关题目：