未知题型 一河道宽b=100m，流量Q=500m3/s，水面坡降J=0.0004，平均水深h=4m，床沙的平均粒径dm=4.5mm，d65=5mm，d90=10mm，泥沙重度γs=26kN/m3，假定推移质与床沙的组成相同，试求推移质输沙率。

未知题型 某孕妇，无业，26岁，经产妇，孕42周，临产25小时仍不能娩出小孩前来就医。检查：阴道口脱出一上肢，恰好与接生者的右手相握，子宫呈葫芦状，子宫下段压痛，胎心不清，胎头在母体右侧，宫口开全，血尿。与本产妇目前疾病诊断无关的是

单项选择题 If you refer to our Sales Confirmation, you will see the clause reading: "The Buyer shall establish the covering letter of credit before 30th August, 2008, failing which the Seller reserves the right to ______ the contract without further notice." A．restrain B．rescind C．recite D．receive