In terms of proofreading, there are a several concerns that you should be alert to. One concern is how the helping verbs to have and to be are used. Other concerns are time relationships in the perfect tenses and whether verbs are regular or irregular.
To have versus To be: To have is used with the past participle to form the perfect tenses.
I have written many papers already this year.
[Present perfect--used to call attention to the duration or repeated
nature of an activity]
The company finally replied, but only after I had
written them several times. [Past perfect--used when for the
earlier of two past events]
I will have written several papers before
this year ends. [Future perfect--used when considering events from
the point of view of some time in the future]
To be is used with the present participle to form the progressive version of any of the six tenses. The progressive version stresses the on-going nature of activities.
I am writing my lab report. [Present progressive]
I have been writing my lab report for almost
three weeks. [Present perfect progressive]
To be is also used with the present participle to form passive voice
The report was written by an assistant to
the company president. [Past tense--passive voice]
The company president approved the report that had
been written by his assistant. [Past perfect tense--passive voice]
Regular versus Irregular Verbs: Regular verbs form their present participle with -ing and their past participle with -ed. The above examples use the verb "write," which is an irregular verb having separate forms for the past participle and the past tense: wrote is the past tense form used for the past tense; written is the past participle used for the perfect tenses and for passive voice. To be is also a very irregular verb: am is the present participle, was is the past tense form and been is the past participle.
Note: A mistake sometimes made by ESL writers is to use to have by itself in combination with the present participle. There is no situation in which this usage is correct, so if you see "have" used to help a verb with an -ing ending without " been" in between, you have a problem!