Approve or disapprove the following statements:
1. Antibiotic substances encourage the growth of microorganisms.
2. Penicillin is the last antibiotic to be produced.
3. Antibiotics are simpler rather small molecular weight substances whose synthesis may be extremely easy.
4. Chloramphenicol can be obtained from the filtrate of various carbohydrates cultures by extraction with ethyl acetate.
5. Chloramphenicol is slowly absorbed from the gastrointestinal tract.
6. The drug is longer detectable in the blood after 12 to 18 hours.
7. Chloramphenicol is marketed in suppositories.

1peter: you (have been telephoning) for ages. have you not nearly (finished)? jack: i (have not got) through yet. i (have been trying) to get our paris office but the line (has been ) engaged all morning. 2 ann (has failed) her driving test three times because she's so bad at reversing. but she (has been practising) reversing for the last week and i think she (has got) a bit better at it. 3 tom: i have often (wondered) why bill left the country so suddenly. peter: actually, i have just (found) out. 4 he (has been playing) the bagpipes since six o'clock this morning. he has only just (stopped). 5 why have you (not brought) me the letters for signature? have you (not typed) them yet? 6 tom (looking up absent-mindedly as mary comes in): have you been (sunbathing)? mary (crossly): don't be ridiculous! it (has been raining) all day! 7 a pair of robins (have been building) a nest in the porch since last week. i (have been watching them from my window since they began. 8 the police (have not found) the murderer yet, but the dead man's brother (has been) in the station all day. the police say that he (has been helping) them with their enquiries. 9 they (have pulled) down most of the houses in this street, but they (have not touched) the old shop at the corner yet. 10 tom is convinced that there is gold in these hills but we (have been searching) for six months and (have not seen) any sign of it. 11 i (have been waiting) for the prices of the houses to come down before buying a house, but i think i (have been waiting) too long and the prices are beginning to go up again. 12 peter (has been) a junior clerk for three years. lately he (has been looking) for a better post but so far he (has not found) anything.

Last month i wanted to make a present for my mother's birthday. i got up early in the morning and quietly went outside. i came to the bus stop to wait for the bus that would take me to the market. when's the bus came i didn't notice what number was written on it. so the bus took me to another part of the city where i have never been. i came out of the bus and looked around. there wasn't anybody nearby. suddenly a little group of young boys came up to me. they asked me if i had any money in my pocket. i said «no» but they didn't believe me. two of them were holding my hands and third one was checking my pockets. they took all my money and ran away. i was very afraid and didn't shout. i understood that i should go back home. but i didn't know how to do it without money. i went to the opposite side of the road and found a bus stop. i was going to wait for the bus but i didn't know how to pay for it. when the bus came and i got into it i explained the driver what happened to me. he felt pity and allowed to go for free. i picked some flowers in neighboring garden and presented it to my mom. luckily she didn’t ever know what an adventure happened to me.