答案：CABCB
词汇讲解
1. initially 最初,开头
She came initially to spend a few days, but in the end she stayed for a whole month.
起先她只打算来待几天，但後来却住了整整一个月。
Initially, I disagree with his proposal, but later I changed my mind.
起初我不同意他的提议，不过后来我改了主意。
2. optimism 乐观,乐观主义
Her mood varied from optimism to extreme depression.
她的情绪由乐观一变而为极度消沉.
They professed optimism about the outcome.
他们对结果表示乐观.