Kitty did not play tennis with her friends last Sunday because it rained heavily.
句意:上周日基蒂没有和她的朋友们打网球,因为雨下得很大。
“because”为原因状语从句的引导词,引导的原因状语从句为陈述句语序。因为雨下的很大意为“because it rained heavily.”。故改成Kitty did not play tennis with her friends last Sunday because it rained heavily.