Do you know why she ___ at home last night? [ ]
A. isn't
B. wasn't
C. not
D. not in
答案:B
图示结构简支梁AB与悬臂梁DE用铰链与弹性杆CD相连。已知q、l、a、EI、E1A,则CD杆的内力为:()
A.(5/16)ql
B.(5/16)ql/[1+(24EIa/E1Al3)]
C.(5/8)ql/[1+(12EIa/E1Al3)]
D.(5/8)ql
()是靠重力和过滤的原理进行除污的。
A、旋流除污器
B、水膜除污器
C、静电除污器
D、锥网除污器