表示"正在進(jìn)行"這一動作，通常用如：I am having a class now.(我正在上課。)但"正在進(jìn)行"這一動作，還可以用"be+介詞短語"來表示。常見的介詞短語類型有： be +at引導(dǎo)的介詞短語;be +in引導(dǎo)的介詞短語;be +on引導(dǎo)的介詞短語; be +under引導(dǎo)的介詞短語等。
Ⅰ.be+at引導(dǎo)的介詞短語 be at war(正在交戰(zhàn))：
The two countries are at war now.兩國正在交戰(zhàn)。
(相當(dāng)于：The two countries are waging a war now.)
be at work(正在工作)：Jim is at work on his car now.吉姆正在修自己的車。
(相當(dāng)于：Jim is repairing his car now.)
be at peace(處于和平或平靜狀態(tài))：
Thus Europe was at peace for the first time in ten years.
于是歐洲在十年以后第進(jìn)入和平狀態(tài)。
be at table(正在吃飯)：When I arrived my friends were already at table.
當(dāng)我到達(dá)時，我的朋友們正在吃飯。
常見的這類結(jié)構(gòu)還有：be at meeting正在開會;be at school正在上學(xué);be at breakfast(lunch /supper)正在吃早(午/晚)飯;be at church正在做禮拜，等等。
Ⅱ.be+in引導(dǎo)的介詞短語 be in progress(正在進(jìn)展)：
The building of the bridge is in progress.
這座橋梁正在施工中。(相當(dāng)于：The bridge is being built now.)
be in trade(正在做買賣)：
Some people of this country are in gold and ivory trade.
這個國家的有些人正在做黃金和象牙買賣。 be in fashion(流行)：
Long hair is very much in fashion now.如今，留長發(fā)正時興。
be in trouble (處于困境/困難之中)：I am in great trouble. My little boy has fallen off a ladder and hurt himself.我遇上點麻煩，我的小兒子從梯子上掉下來，并且摔傷了。
常見的這類結(jié)構(gòu)還有：be in danger處在危險中;be in operation正在運行; be in action在活動(運轉(zhuǎn)/戰(zhàn)斗)中;be in peril在危險之中;be in class正在上課;be in hospital 正在住院;be in office在執(zhí)政;be in tears正在流淚;be in milk正在產(chǎn)奶;be in issue正在爭論之中; be in church正在做禮拜;等等。
Ⅲ.be+on引導(dǎo)的介詞短語
be on strike(正在罷工)：The electricity workers have been on strike for several weeks now.電力工人到目前已經(jīng)罷工好幾個星期了。(即現(xiàn)在仍在罷工)
be on leave(正在休假)：Several soldiers are on leave in our village.幾位軍人正在我們村子里休假。
be on the rise(正在上漲)：Prices of vegetables are on the rise.蔬菜價格正在上漲。
常見的這類結(jié)構(gòu)還有：be on a visit正在訪問;be on the stumps處在困難之中;be on sale正在出售(美語作：削價出售)，等等。
Ⅳ.be +under引導(dǎo)的介詞短語
be under consideration(正在考慮之中)：The plan is under consideration by the Ministry of Education.教育部正在考慮這項計劃。
be +under construction(正在修建中)：The new railway is still under construction.新鐵路仍在修筑之中。
be +under discussion(正在討論之中)：That issue has no relation to the matter under discussion.那個問題和正在討論的事沒有關(guān)系。
常見的這類結(jié)構(gòu)還有：be under treatment正在治療中;be under repair正在修理中，等等。
值得英語學(xué)習(xí)者注意的是
?、疟M管be+介詞短語能表示"正在進(jìn)行"這一意義，但它和be+現(xiàn)在分詞所表示的語法意義是有差別的。前者著重事物所處的狀態(tài)，偏重于靜態(tài);后者著重事物的動態(tài)，集中表示事物的動感。
?、?絕大部分這類結(jié)構(gòu)，其名詞前都沒有冠詞，假如加一冠詞，意義將大相徑庭。如：The Conservative Party is in office.保守黨在執(zhí)政。The principal is now in the office.校長現(xiàn)在在辦公室。英語學(xué)習(xí)者對上述差別決不可掉以輕心。