(1) oughta be a gentleman, since his name is William. 

(2) I have long since abandoned the notion that higher education is essential to either success or happiness. Hot houses of learning do not always grow anything edible. 

(3) Since a politician never believes what he says, he is surprised when others believe him. Charles de Gaulle 

(4) The rain has been continuous since this morning.

(5) Children have been routinely immunized against polio since 1958.

(6) It's yonks since we had a good night out.

(7) Forty years have passed away since they met.

(8) He's been deaf and dumb since birth.

(9) They've been best friends since they were children.

(10) It's all sewn up(sentencedict.com), since you apologized.

(11) I have been there many times since the war.

(12) He's been unbearable since he won that prize.

(13) She's lived there since before the war.

(14) Since you unintentionally I should let it go.

(15) I haven't heard from him since last January.

(16) He's got rather plump since I last saw him.

(17) Her father has been missing since September 1992.

(18) Since childhood, her life has revolved around tennis.

(19) He has been an orphan since he was five.

(20) We've been pals since we were at school.

(21) Since the war the industry has gradually languished.

(22) She's been off work since Tuesday.

(23) It's many years since Mount Vesuvius last erupted.

(24) She has fined down a lot since last year.

(25) We've been mates since our school days.

(26) Two weeks have lapsed since they arrived in Paris.

(27) He's been working in a bank since leaving school.

(28) It's been ages since we met.

(29) The laws of Nature, that is to say the laws of God, plainly made every human being a law unto himself, we must steadfastly refuse to obey those laws, and we must as steadfastly stand by the conventions which ignore them, since the statutes furnish us peace, fairly good government and stability, and therefore are better for us than the laws of God, which would soon plunge us into confusion and disorder and anarchy if we should adopt them. 

(30) Be not angry that you cannot make others as you wish them to be, since you cannot make yourself as you wish to be.