可以做：
副词,
Surely, she won?t go to China Telecom with you（Surely）
形容词或其短语,
Strange to say (或True), he should have done such a thing.（Strange to say (或True））
介词短语,Of course, he did not succeed for the lack of experience.（Of course）
分词短语?,
Judging from his letter, a campaign against“white pollution”has been underta ken in his hometown.（Judging from his letter）
不定式短语,
To be sure, community service can aid re?employment.?（To be sure）
句子
One day, it is said, Newton saw an apple fall from a tree.（it is said）
括号里的为插入成分……