How is [((英))are] your family?
ご家族の皆さんはお元気ですか
How kind of you!
ご親切にどうも
How likely [true] is that?
そんなのありえない
How long did the movie last?
映画はどれくらいの長さだった?
How long is the bridge?
橋の長さはどれくらいか
How long shall you be in London?
ロンドンにはどれほど滞在のご予定ですか(◆willやbe going toを用いるほうがよい)
How long this will last is anybody's guess.
どれぐらい続くかだれもわからない
How lovely to see you again!
また会えてうれしいわ
How lucky [sad] is that?
なんて幸運だ[悲しい]
How many books do you read per year?
1年に何冊読む?