A:So difficult a question did he ask me
B:Such difficult a question did he ask me
C:Such a difficult question he asked me
D:He asked me a so difficult questio
将下列陈述句改成反问句
①您吃过饭了。
②有一位管家求见。
用科学计算器计算:8+3sin56°≈____.(精确到0.01)
生产、生活中常用的木材主要是利用了木本植物茎的哪一部分( )
解方程组:x-1=02x-y+z=-1-x+y+z=0