(17)に引き続き，(18)です。1999年のを見ます。
次の (A) ～ (F) の各文には一箇所ずつ，文法的な誤りがある。その場所を答えよ。
(A) One way to deal with the problem were to be suggested by the committee.
(B) I would appreciate very much if you could show me how to put the machine back together.
(C) By the time the messenger arrives, the gate will have been opened to let in him.
(D) Everyone who saw them work was amazed by their ability of using so many different kinds of machines at once.
(E) For those of you who don't exercise regularly, it will probably be extremely difficult to keep to run for more than 30 minutes.
(F) I don't think Mary could have been the one who somehow managed to put out the fire, although she is possible to have called the fire department.
可能なら場所を言うだけでなく，どう直すべきかも答えてみて下さい。
では解説に入ります。
(A) One way to deal with the problem were to be suggested by the committee.
この文の主語は単数形の One です。よって動詞は was でなければなりません。
One way to deal with the problem was to be suggested by the committee.
was to be suggested の部分は，〈予定の be to〉に受け身の be suggested が続き，「提案される予定だった」「提案されることになっていた」です。
(B) I would appreciate very much if you could show me how to put the machine back together.
I would appreciate it if you could [would] V「もし V して下されば有難いのですが」は決まり文句としてしっかり覚えておきましょう。
I would appreciate it very much if you could show me how to put the machine back together.
put O together は「組み立てる；（考えを）まとめる」です。put the machine back together は「この機械をもう一度組み立て直す」という意味でしょう。
(C) By the time the messenger arrives, the gate will have been opened to let in him.
By the time S V「S が V するまでには」は時を表す副詞節を導くので，arrives という現在形で OK です。will have been opened の所は〈未来完了〉が使われており，「（門は）開かれていることだろう」です。最後の let in him が誤りで，him のような代名詞一語の場合は let him in となります（例．give it up）
By the time the messenger arrives, the gate will have been opened to let him in.
(D) Everyone who saw them work was amazed by their ability of using so many different kinds of machines at once.
個人的にはやや難しいかなと思いましたが，受験生は
「V できること」は ability to-V と言い，❌ability of Ving とは言わない
と覚えてしまって下さい。これで瞬殺です。
Everyone who saw them work was amazed by their ability to use so many different kinds of machines at once.
なぜ難しいと思うと言ったかというと，英語の歴史の中で ability of Ving という言い方が一度もなされたことがないというわけではないからです。私は今『ジーニアス英和辞典』のほか，電子版『ランダムハウス英和大辞典』も持っているのですが，『ランダムハウス』は ability の例として He has no ability to-V... を紹介し，そこに「🔶of doing の形が用いられることもある」と書いてあるのです。ただ余り普通ではないのでしょう。受験では不可くらいに覚えてしまいましょう。be able to-V → ability to-V と連想しましょう。
(E) For those of you who don't exercise regularly, it will probably be extremely difficult to keep to run for more than 30 minutes.
これは簡単でしょう。「V し続ける」は keep Ving（keep on Ving）です。
For those of you who don't exercise regularly, it will probably be extremely difficult to keep running for more than 30 minutes.
(F) I don't think Mary could have been the one who somehow managed to put out the fire, although she is possible to have called the fire department.
これも高校レベルです。❌She is possible to-V「彼女は V する可能性がある・することができる」という言い方はありません。⭕️It is possible for her to-V のように言わなければなりません。
I don't think Mary could have been the one who somehow managed to put out the fire, although it is possible for her to have called the fire department.
I don't think Mary could have been the one who somehow managed to put out the fire, although she could have called the fire department.「メリーがどうにかして火を消した本人であったとは思わない。もっとも彼女が消防署に電話した可能性はあるが」
いかがでしたでしょうか。どれもできて良い問題ですが，本番は時間制限もあるので短時間で指摘するには英語に慣れ親しんでいる必要があるのでしょうね。
次回は2000年を見たいと思います。
