2022-2023英语周报九年级第37期答案

61. danger 62. an 63has doubled 64. as 65. earlier66. commonly 67. to achieve68. including 69. saying70, and71.charged 72. meed 73. traditionally 74. colleagues75. claims76. stresses 77. situated 78 polluted 79 possibility 80. argument

12.选D对于A,取CD中点F,连接MF,BF,则MF∥A1D且MF=3A1D,FB∥ED且FB=ED,由MF∥A1D与FB∥ED,A1D∩ED=D,MF∩FB=F,可得平面MBF∥平面A1DE,∴总有BM∥平面A1DE,故A正确;对于B,在矩形ABCD中,AB=2AD=2,E为AB的中点,得ED2=12+12=2=CE2,CD2=22=4所以CE2+ED2=CD2,∠CED=90°,∴,CE⊥ED,MF∥A1D,且MF2A1D,FB∥ED,FB=ED∠A1DE=∠A1ED=∠MFB=45°,由余弦定理,得MB=√BF+MF=2BF· MFcs∠MFB=,故B正确;对于C,因为M为A1C的中点,所以VA-DEM=VA.-CDE,设点A1到平面ABCD的距离为h,所以VA=EM=1A-CDE×S△ CDE Xh=-××言×1×2×h当平面A1DE⊥平面ABCD时,三棱锥A1-DEM的体积取得最大值,且hmax=y2,所以三棱锥A1DEM的积最大值为×=1,故C正确;对于D,若平A1DE⊥平面A1CD,则EA1⊥A1C,∵EA1=1,EC√2,则A1C=1,此时点A1在平面ABCD上,故不存某个位置,使得平面A1DE⊥平面A1CD,故错误选D

以上就是2021-2022英语周报九年级第37期答案，更多英语周报答案请关注本网站。