翻云覆雨
[词典] shifty; as changeable as clouds and rain; blow hot and cold; change attitudes constantly; fickle as human feelings;
[例句]他这个人翻云覆雨，弄不清他究竟主张什么。
He's a man given to blowing hot and cold; you just can't tell what he's standing for.
厚积薄发
[词典] accumulate richly and break forth vastly;
[例句]今天的合肥，已迈入一个厚积薄发、加速崛起的新阶段。
And today's Hefei is entering a new stage of well-grounded development and accelerated emergence.