can any 1 answer this puzzle?

Question

Across
1 Star like curve (7)
4 An abbreviation for infimum. (3)
6 The Greek letter equivalent in sound to the English t. (3)
8 A way of writing a something using numbers and symbols (10)
10 Prefix meaning three. (3)
11 A logical operator which gives the result 'false' if both of its arguments are false, and 'true' otherwise. (2)
12 A figure has this if it remains the same after a reflection or a rotation of less than a whole turn. (8)
16 Equivalent to 1 millilitre. (abbreviation) (2)
17 The volume of a cube whose sides are 1m long. (5,5)
19 Any instrument for measuring time. (11)
22 A prefix meaning 1000000000000000000 (3)
24 A special subgroup of a ring. (5)
26 Two tetrahedra are said to be this if each edge of one meets two opposite edges of the other. (6)
Down
1 Pi times radius times radius (4,2,6)
2 Short for ordinary differential equation. (3)
3 A circle, including not just its edge but also its inside. (4)
4 Two shapes whose perimeters are the same length are this. (13)
5 An abbreviation for foot or feet. (2)
7 To do with one. (3)
9 The ratio of the circumference of a circle to its diameter. (2)
10 An abbreviation for the trace of a matrix. (2)
13 A prefix meaning 1/1000000000000000000000000 (5)
14 A mystery; something to which the answer is unknown. (6)
15 The simplest knot with three crossings. (7)
18 The second prime number (5)
20 A public key encryption algorithm (3)
21 The SI unit of moment. (2)
23 Says 'ks' in Greek. (2)
25 The number of years following the birth of Jesus Christ. (2)

Answer 1

1 cycloid

4 inf

6 t

8A encryption

10 tri

11 or

12A symmetry

16 ml

17 cubic meter

19 chronometer

22 exa

24 ideal

26 ???

Down
1 area of circle

2 ode

3 disc (USA spelling: disk )

4 isoperimetric

5 ft

7 uni

9 pi

10 tr

13 yocto

14A enigma

15 trefoil

18 three

20A rsa

21 Nm

23 xi

25 AD

Answer 2

Here are the ones I can get off the top of my head...

across:
8 - cryptology
10 - tri
12 - symmetry
17 - cubic meter
19 - chronometer

down:
1 - area of circle
5 - ft
9 - pi
14 - enigma
18 - three
25 - AD

Answer 3

Number 25 could be 2007 the rest i will get back to u in five minutes.