This research introduced mobile devices into an intensive reading course and allowed functions that are usually found only in the language laboratory to be easily and flexibly utilized in the general classroom. To enhance and improve the reading comprehension of English as a foreign language (EFL) readers, a computer-assisted-language-learning (CALL) system for use on PDAs, integrating an instant translation mode, an instant translation annotation mode, and an instant multi-users shared translation annotation function was developed to support a synchronously intensive reading course in the normal classroom. Experiments were conducted to analyze the usage of the system, including the attitude and satisfaction of users. Moreover, the study determined the optimum number of users in each group for the system to work most efficiently, and for students to improve their reading comprehension. Experimental results indicated that those students who were grouped into twos, threes, and fours had significantly higher levels of comprehension than individual students, but those grouped into fives did not. Overall, on average around 70% of the students agreed that the system was useful, 75% of the students agreed that the system was easy to use, and 66% of the students perceived satisfaction with the system. The user intentions were also further analyzed in light of a path analysis method.