Trong cấu tạo của tế bào thực vật, bào quan nào thường có kích thước rất lớn, nằm ở trung tâm tế bào và đóng vai trò quan trọng trong việc duy trì áp suất thẩm thấu ?

A. Nhân

B. Không bào

C. Ti thể

D. Lục lạp

Có bao nhiêu số nguyên m để phương trình sin 2 x - sin   x   = m + 2 m + 3 sin   x  có nghiệm thực

A. 7.

B. 2.

C. 3.

D. 6.

Cho ba lực đồng quy cùng nằm trong một mặt phẳng có độ lớn F₁ = F₂ = F₃ = 15N và từng đôi một hợp thành góc 120⁰. Tìm hợp lực của chúng.

A. 15 N.

B. 45 N.

C. 30 N.

D. 0 N.

Đề hình như sai rồi nhé! phải là giá trị nhỏ nhất mới đúng

\(\left|x^2+2015\right|-3\)

Vì \(\left|x^2+2015\right|\ge0\)

\(GTNN\left(\left|x^2+2015\right|\right)=0\)

\(GTNN\left(\left|x^2+2015\right|-3\right)=0-3=-3\)

146. The earth depends on the sun for its head and light.

147. Ahhh! I am trying to concentrate. I can't hear myself think with all that noise going on.

148.Mrs Lien is at the market. Right now, she is looking at the apples. They look fresh.

149. Nam didn't hear his parents having a argument last night. He was listenning to music in his room.

150. When I was a child, my mother always served cookie and milk to my friends and me when we went to my home after school.

151. Jane is expecting the letter from me but I haven't written to her yet.

152. Let's stop at the next hotel. We have driven 500 miles so far to day and that's enough.

153. Every one makes mistakes in life. I make  lots of mistakes in my life. The important thing is to learn from one's mistake. Right?

154. I understand Tom is good friend of yours? 

-How long have you known him?

-Since we were kids.

155. My wife and I have moved three times since we got married. 

156 I knew Tim when he was a child but I haven't seen him for many years.

157. Nga missed her English examinaion this morning because she overslept. She has overslept a lot since the benning of the semester. She'd better buy a new arlarm clock.

158. Jack really needs to get I touch with you. Since this morning, he has called here four times trying to reach you. He called at 9:10;10:25;12:25 and 1:45.

159. Alex is an artist. He has drawn many beautiful pictures in his lifetime. Last week, he drew a beautiful mountain scene.

160. The world has enjoyed Beethoven's music for nearly 200 years. 

161. Since I learned that cigarettes cause cancer, many people have stopped smoking.

162. I've come without any money.

-Never mind. I will lend you some.How much do you want?

163. I am catching the 6:30 train.

-So am I. I will give you a lift to the station.

164. Look at those black clouds. It is going to rain.

165. The old man fell as he got into the bus yesterday.

166. The earth moves around the sun.

167. Something smells good in the kitchen now.

168.I tidied my desk, but now it isn't in a mess again.

169. The last time I went to Brighton was in August.