call in:      
(1) 叫…進來；叫…進去  
ask to come or go in 
[例句] 

     Please call Comrade Shen in. 
     請叫沈同志進來。 
     I waited for only two minutes before I was called in. 
     我只等了兩分鐘就被叫進去了。 
(2) 邀請召來；召去  
invite: summon 
[例句] 

     He called all the workers in for a conference. 
     他召集全體工人開會。 
     How many friends did you call in? 
     你邀請了多少朋友？ 
     Let's call in a doctor for the baby. 
     讓我們請上醫(yī)生來瞧瞧這孩子吧。 
call on

1) 拜訪

I'll call on him tomorrow. 

明天我去拜訪他。

2)號召；呼吁

3)邀請

call at:     到…作短暫訪問  
pay a short visit at 
[例句] 

     We called at Li's house yesterday. 
     我們昨天到李家訪問。 

call up:      

(1) 打電話給  
make a telephone call to 
[例句] 

     Call me up tomorrow：my telephone number is 536291。 
     請明天打電話給我：我的電話號碼是536291。 
(2) 打電話  
make a telephone call 
[例句] 

     This morning someone called up from downtown and asked to see me at two o'clock. 
     今天早上有人從市里打電話來，要求在兩點鐘時來看我。 
(3) 喚醒  
arouse from sleep 
[例句] 

     Shall I call you up at six tomorrow morning? 
     我明天早上六點鐘叫醒你好嗎？ 
     The doctor was called up three times last night. 
     昨夜醫(yī)生三次被從床上叫起來看病。 

call for:      

(1) 喊著要人取來（某物）；喊著要（某人）來  
ask in a loud voice for (sth. or sb.) to be brought or to come 
[例句] 

     I'll call for it on my way home this evening. 
     我今晚回家時順便來取。 

(2) 去�。粊砣�；去或來接（某人）  
go or come to fetch;go or come to take (sb.) 
[例句] 

     She called for the books she had lent me. 
     她來拿回她借給我的書。 
(3) 需要  
require 
[例句] 

     Every step forward made by the revolutioon calls for a struggle. 
     革命每前進一步都得經(jīng)過斗爭。 
     The baby is calling for his mother. 
     嬰孩叫著要母親。 
(4) 要求  
demand 
[例句] 

     Our class calls for a debate on the subject. 
     我們班級要求對這個問題進行辯論。 
     I'm afraid what I said just now was not called for. 
     恐怕我剛才說的話本來是不必講的。 
     More work does not necessarily call for more men. 
     增加工作不一定需要增添人員。 

call off:      

(1) 喊走；把…叫走  
tell in a loud voice to go away 
[例句] 

     Please call off the dog; it's barking at the children. 
     請把這條狗喝走，它在對著孩子們吠叫。 
(2) 命令；停止做某事  
order to stop doing sth. 
[例句] 

     When the lost child was found, the commune members searching for him were called off. 
     當走失的小孩找到時，還在尋找他的社員們接到通知不再尋找了。