Konna taihenna shigoto, ichinichi-de dekiru wake-ga nai-yo. (Finishing work this tough in a day is just not possible.)

Situation 1: Ms. Gray talks to her colleague Mr. Mita about a client's request.

グレイ： お客さまはあしたまでに見積もりを出してほしいって言っているんだけど。

三田： ええっ、こんな大変な仕事、１日でできるわけがないよ。しめきりはせめて３日後じゃないと。

Gray: O-kyaku-sama-wa ashita-made-ni mitsumori-o dashite-hoshii-tte itte-irun-da-kedo.

Mita: Ee', konna taihenna shigoto, ichinichi-de dekiru wake-ga nai-yo. Shimekiri-wa semete mikka-go-ja-nai-to.

Gray: The customer says that he wants the estimate by tomorrow.

Mita: What? Finishing work this tough in a day is just not possible. The deadline should be at least three days after [submission].

Today we will introduce two expressions — わけがない and はずがない — that express strong denial. Xわけがない means "there is no reason for X/it cannot be X" and is used when the speaker wants to deny the possibility of X subjectively. Here, X is a noun-modifier in nonpast tense. Examples: いくらがんばっても私(わたし)が オリンピック選手(せんしゅ)に勝(か)てるわけがない (However hard I try, there's no way I can beat an Olympic athlete); 彼(かれ)は今 (いま)、熱(ねつ)があるのだから、元気(げ んき)なわけがない (He has a fever right now, so it's only natural that he's not cheerful). X can be a negative sentence, as in こんな簡単(かんたん)なことばをリーさんが知(し)らないわけがない (There is no excuse for Mr. Lee not knowing such an easy word).

Situation 2: In a meeting room, Mr. Mita and Ms. Gray are waiting for Ms. Tamachi to arrive.

三田： 田町さんがまだ来ないね。忘れているのかな。

グレイ： あのまじめな田町さんが会議を忘れるはずがないよ。

Mita: Tamachi-san-ga mada konai-ne. Wasurete-iru-no-kana.

Gray: Ano majimena Tamachi-san-ga kaigi-o wasureru hazu-ga nai-yo.

Mita: Ms. Tamachi isn't here yet. Has she forgotten?

Gray: There is no way an earnest person like her would forget a meeting.

Xはずがない also has a similar meaning to Xわけがない, and in most cases they are interchangeable. However, Xはずがない implies that there is a logical reason involved, while わけがない can be used even when there isn't. Example:こんなに安(やす)いんだから、本物(ほんもの)のダイヤのはずがない (With the price so cheap, this one can't be a real diamond). There are two negative patterns using はず: Xはずがない (as in 知っているはずがない) and Xないはずだ (as in 知らないはずだ). Of the two, Xはずがない negates X more strongly.

Bonus Dialogue: Junior high school student Takako talks to her mother about her elder brother, Mitsuo.

たか子： きのう、お兄(にい)ちゃんがすごくかわいい子(こ)といっしょに歩(ある)いていたよ。

母： まさか。光男(みつお)のはずがないでしょ。きのうは部活(ぶかつ)だったんだから。それに、光男がそんなかわいい子とデートするわけがないわよ。

たか子： そうかなあ。きのうもおやつを食(た)べなかったし。恋(こい)の悩(なや)みがあるんじゃない？

母： 光男に食欲(しょくよく)がないわけがないでしょ。ちょっと前(まえ)に何かを食べてお腹(なか)がいっぱいだったのよ、きっと。

たか子： お母さん、お兄ちゃんのこと、わかってないよ。あれでもけっこう女の子に人気(にんき)があるんだよ。サッカーとかうまいし。

母： ええっ、ほんとうなの？

たか子： そうだよ。そんなはずがない、とか言(い)ってばかりいると、お兄ちゃんのことがわからなくなるよ。親(おや)なんだから、しっかりしてよ。

母： はい、はい、わかりました。それにしても、光男がねえ...。

Takako: I saw my brother walking with a very pretty girl yesterday.

Mother: No way! That can't have been Mitsuo, surely? He was doing club activities yesterday. Besides, Mitsuo wouldn't be going out with such a pretty girl.

Takako: I wonder. He didn't eat his afternoon snack yesterday. Perhaps he's worried about his love life.

Mother: There's no way that he wouldn't have an appetite. He must've eaten something just before that.

Takako: Mom, you don't know him at all, do you? He's quite popular with girls. He's good at soccer and stuff too.

Mother: What? Are you serious?

Takako: I'm serious. If you always say everything's impossible, you won't be able to understand him. Mom, you're his parent — please act like it!

Mother: OK, OK, I get it. But still, it's Mitsuo ...