【单选题】
计算工字形梁的抗弯强度，用公式Mx/yxWnx≤f,取yx=1.05梁的翼缘外伸肢宽厚比不小于（）。
①
<imgalt=""src="http://wljy.whut.edu.cn:80/uploadfiles/kindeditorAttached/image/20191203/20191203173347_758.png"/>
②
<imgalt=""src="http://wljy.whut.edu.cn:80/uploadfiles/kindeditorAttached/image/20191203/20191203172523_453.png"/>
③
<imgalt=""src="http://wljy.whut.edu.cn:80/uploadfiles/kindeditorAttached/image/20191120/20191120171553_415.png"/>
④
<imgalt=""src="http://wljy.whut.edu.cn:80/uploadfiles/kindeditorAttached/image/20191203/20191203173359_603.png"/>
【单选题】
It is[填空]picture of[填空]elephant on[填空]wall.
①
a,an,the
②
a,the,an
③
the,a,an
④
an,a,the