A Content Writer is expected to be grammatically correct and international clients will expect nothing but the best written material which they won't require to proofread after having paid anything between $ 8-15 per article. So any reputed company is likely to test your grammar skills before going to the second round. Most of the grammar tests focus on punctuation, verb and conjunction usage and few other topics. So brush up, or more correctly, dust off the cobwebs by going through that family heirloom called Wren & Martin.