Like1 as a conjunction meaning “as, in the same way as” ( Many shoppers study the food ads like brokers study market reports ) or “as if” ( It looks like it will rain ) has been used for nearly 500 years and by many distinguished literary and intellectual figures. Since the mid-19th century there have been objections, often vehement, to these uses. Nevertheless, such uses are almost universal today in all but the most formal speech and writing. In extremely careful speech and in much formal writing, as, as if, and as though are more commonly used than like : The commanding general accepted full responsibility for the incident, as any professional soldier would. Many of the Greenwich Village bohemians lived as if (or as though ) there were no tomorrow.
The strong strictures against the use of like as a conjunction have resulted in the occasional hypercorrect use of as as a preposition where like is idiomatic: She looks as a sympathetic person.
Like meaning “as if” is also standard in informal speech and writing with a small number of adjectives: The crew worked like crazy (or like mad ) to finish the job on time. See also as.